Cauliflower and Broccoli Casserole with Bacon

Name: Cauliflower and Broccoli Casserole with Bacon
Ingredients: 4 tbsp. salted butter, plus more for the baking dish; 1 tsp. kosher salt, plus more to taste; 5 c. cauliflower florets; 5 c. broccoli florets; 2 c. crushed butter crackers; 1/2 tsp. paprika; 6 slices bacon; 2 garlic cloves, finely chopped; 3 tbsp. all-purpose flour; 1 tsp. ground mustard; 1 tsp. grated lemon zest; 1/4 tsp. cayenne pepper; 2 1/2 c. whole milk; 4 oz. cream cheese, at room temperature, cubed; 2 c. grated mild cheddar cheese