Butternut Squash and Kale Strata | culture: the word on cheese

Ingredients

• 3 tablespoons olive oil (divided)
• 2 yellow onions (thinly sliced)
• Kosher salt (to taste)
• Freshly ground black pepper (to taste)
• 2 cloves garlic (minced)
• 2 teaspoons chopped fresh thyme
• Pinch red pepper flakes
• 12 ounces kale (ribs discarded and leaves chopped)
• 2 tablespoons unsalted butter
• ¼ cup all-purpose flour
• 2½ cups whole milk (divided)
• 1 cup heavy cream
• ½ cup sour cream
• 8 large eggs
• 1 pound loaf crusty multigrain bread (cut into 1-inch pieces)
• 2 pounds butternut squash (peeled and diced)
• 1 cup grated smoked cheddar cheese (divided)