Cinnamon Streusel Swirled Maple Sweet Potato Casserole

Bahan-bahan (8 porsi)

• 4 medium sweet potatoes
• 1/4 cup real maple syrup
• 2 teaspoons vanilla extract
• 1 teaspoon ground cinnamon
• 1/4 cup heavy cream
• 4 tablespoons salted butter, melted
• 2 eggs, lightly beaten
• 1/2 cup all-purpose flour
• 1/2 cup brown sugar, packed
• 1/2 cup real maple syrup
• 1 cup raw walnuts, finely chopped
• 1 teaspoon cinnamon
• 8 tablespoons cold butter, cubed