Sour Cream Coffee Cake with Cinnamon-Walnut Swirl - Once Upon a Chef

Ingredients

• 1 heaping cup walnut halves, roughly chopped
• 3 tablespoons packed light brown sugar
• 2 teaspoons cinnamon
• 2⅓ cups all-purpose flour, spooned into measuring cup and leveled-off
• ½ teaspoon baking soda
• 1 teaspoon salt
• 2 cups granulated sugar
• 2 sticks (1 cup) unsalted butter, room temperature
• 3 large eggs
• 1 (8 oz) container full fat sour cream
• 1½ teaspoons vanilla extract