Makes8 servings 
                    
                
                
                    
                        
                            - Active time: 45 min
Total time: 1 1/2 hr 
                        
                    
                
             
            
                
                    
                    Kale and cauliflower get cozy in this gratin. The crisp, cheesy breadcrumbs and silky béchamel sauce are the perfect bedfellows for these vegetables.
                
            
            
                
                
                
    
      
  
                
                
            
            
            
            
            
            
            
                
                    
                    
                    
                        
                            INGREDIENTS:
                            
                            
                                
                                    
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                                            1 3/4
                                            
                                            pounds curly kale (about 3 bunches)
                                            
                                        
 
                                    
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                                            2
                                            
                                            small heads cauliflower (about 4 pounds total)
                                            
                                        
 
                                    
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                                            5
                                            
                                            tablespoons unsalted butter
                                            
                                        
 
                                    
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                                            1/4
                                            
                                            cup all-purpose flour
                                            
                                        
 
                                    
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                                            2
                                            
                                            cups milk
                                            
                                        
 
                                    
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                                            1
                                            
                                            cup heavy cream
                                            
                                        
 
                                    
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                                            1 3/4
                                            
                                            cups coarse fresh bread crumbs (from firm white sandwich bread; about 3 slices)
                                            
                                        
 
                                    
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                                            1 1/2
                                            
                                            tablespoons extra virgin olive oil
                                            
                                        
 
                                    
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                                            1/2
                                            
                                            cup grated Parmigiano-Reggiano
                                            
                                        
 
                                    
                                
                            
                         
                    
                 
            
            
            
            
            
            
            
            
                
                    
                    
                    
                        
                            
                        
                            
                                INSTRUCTIONS:
                                
                                
                                    
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Tear kale leaves from stems and center ribs, then discard stems and ribs.
                                         
                                    
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Cut and discard greens and core from cauliflower, then cut cauliflower into 1 1/2-inch florets.
                                         
                                    
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Have ready a large bowl of ice water. Butter baking dish.
                                         
                                    
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Cook kale in a pasta pot of boiling salted water, uncovered, in 2 batches until almost tender, about 3 to 5 minutes per batch. Transfer with a slotted spoon to ice water to stop cooking, then transfer with tongs to a colander to drain. Gently squeeze excess water from kale by handfuls and transfer to baking dish.
                                         
                                    
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Cook florets in 1 batch in pot until crisp-tender, about 3 to 6 minutes, then transfer with slotted spoon to ice water to stop cooking and drain well in colander. Nestle cauliflower in kale.
                                         
                                    
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Preheat oven to 375°F with rack in lower third.
                                         
                                    
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Melt butter in a 3-quart heavy saucepan over medium-low heat. Whisk in flour, then cook roux, whisking frequently, 3 minutes. Whisk in milk and cream and bring to a boil, whisking constantly. Reduce heat and simmer béchamel sauce, whisking occasionally, 5 minutes, then stir in 1 1/2 teaspoons salt and 1/4 teaspoon pepper. Pour sauce over kale and cauliflower.
                                         
                                    
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Toss together bread crumbs, oil, cheese, and 1/8 tsp each salt and pepper, then sprinkle evenly over mixture and bake gratin in oven until sauce is bubbling and crumbs are golden, 40 to 45 minutes.
                                         
                                    
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If you wish the crumbs to be more golden, broil gratin under a preheated broiler, about 6 inches from heat, watching carefully, 1 to 2 minutes.
                                         
                                    
                                
                             
                        
                            
                                COOKS’ NOTES:
                                
                                
                                    
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Crumb mixture can be made 2 days ahead and chilled in an airtight container.
                                         
                                    
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Kale and cauliflower in sauce can be assembled 1 day ahead without crumb topping and chilled, covered.