Start by preheating your oven to 375F and spraying a muffin tin with nonstick spray. Line the muffin tin with paper cupcake liners and set aside.

In a large bowl, beat together the brown sugar and melted butter until smooth, using a hand mixer or stand mixer.

Add the eggs, vanilla extract, pumpkin purée, and greek yogurt. Mix the wet ingredients until well combined.

In a separate bowl, whisk together the flour, baking soda, salt, pumpkin spice, and cinnamon.

Add the dry ingredients and wet ingredients together until well combined. Do not overmix the pumpkin muffin batter. Leave the batter to rest at room temperature while you prepare the streusel topping.

In a medium bowl, combine flour, brown sugar, and cinnamon. Add the melted butter and mix with a fork until crumbly.

Fill each of the paper liners 3/4 of the way full of pumpkin batter. Sprinkle crumb streusel topping evenly across the top of the muffins.

Bake the pumpkin spice muffins in the oven for 18-20 minutes, or until a toothpick inserted in the center of the batter comes out clean.

Let them cool in the muffin pan for 5 minutes, before transferring to a wire rack to cool completely.

In a small bowl, start preparing the cream cheese topping. Beat the cream cheese until smooth. Add the confectioners sugar, vanilla extract, and 1 tablespoon of milk. Beat until creamy, adding additional milk until you reach your desired consistency.

Once the pumpkin muffins are cooled, spread the cream cheese frosting over the muffin tops or pipe with a piping bag. Enjoy your delicious pumpkin dessert!