Preheat oven to 350ºF. Line a muffin tin with paper liners or spray with nonstick cooking spray.

In a mixing bowl, whisk together the flour, baking powder, baking soda, salt and spices until well incorporated; set aside.

In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, oil, and sugars together until smooth. Add the eggs, beating after each addition, followed by the pumpkin, sour cream, and vanilla. Stir in the dry ingredients until just combined. Try not to over mix.

Scoop batter into lined muffin tin, filling about 3/4 full; set aside while you make the streusel.

In a small saucepan, melt the butter over medium-low heat. As the butter melts, it’ll start to foam, then turn a clear golden color. Continue to stir the butter, scraping up any browned specks from the bottom of the pan as it starts to brown. It should have a nutty aroma.

Once browned and nutty, turn off the heat and allow to cool for 5 minutes. Add the flour, brown sugar, nuts, and cinnamon, and stir with a fork until it resembles clumps of sand.

Spoon about a tablespoon of the streusel on top of each muffin, making sure that all of the batter is covered. Bake for 20-24 minutes, or until a toothpick inserted in the center comes out with few crumbs attached. Allow muffins to cool in the muffin tin for 10 minutes before transferring to a wire rack to cool completely.

As the muffins cool, prepare the glaze by melting the butter and maple syrup together in a small saucepan over medium heat. Once the butter has melted, remove pan from heat and whisk in the sifted powdered sugar. Allow to cool for 5 minutes to thicken before generously drizzling over the muffins. Serve and enjoy!