• Preheat oven to 350 F. Prepare a muffin tin with liners in each cup.

Streusel:

• In a medium microwave-safe bowl, melt 4 tablespoons of butter. Using a fork, mash together the melted butter, ⅔ cup brown sugar, ½ cup flour, and 1 tsp cinnamon until combined and crumbly. Set aside.

Cream Cheese Swirl:

• In a medium mixing bowl, beat the cream cheese and egg yolk together until smooth. Add in the powdered sugar and vanilla extract, mix until combined. Set aside.

Muffins:

• In a medium microwave-safe mixing bowl, melt the ½ cup of butter. Pour the granulated sugar and brown sugar into the bowl with the melted butter and combine.
• Stir in the 2 eggs, vanilla extract, and sour cream.
• Add the 1 ½ cups of flour, baking soda, baking powder, pumpkin pie spice, and cinnamon sugar. Mix all until just combined. Stir in 2 tablespoons of milk.
• Fill each muffin liner ⅔ of the way with the muffin batter. Add a tablespoon dollop or so of the cream cheese mixture. Using a toothpick, swirl the cream cheese mixture until it’s marbled throughout. Make sure to not over-mix.
• Top with a teaspoon or so of streusel… or more if you would like! Then bake on 350 F for 25 minutes or until they’re not jiggly in the center and golden brown on top.