Brown Butter Pumpkin Muffins

Start with the streusel topping by placing the cashews, flour, brown sugar, and oats in a food processor. Blend until combined, then add the butter and blend again until the mixture becomes crumbly. (If you do not have a food processor, whisk the dry ingredients together in a bowl, then stir in the butter until the mixture forms crumbs.) Set into the refrigerator to chill.
Spray a muffin tin with baking spray and set aside.
Set the butter into a small pan over medium heat and warm until all of the butter has melted, and it begins to crackle and pop, turn brown, and milk solids separate and float to the bottom of the pan, approximately 5-7 minutes. Remove from heat and set aside to cool slightly.
In the bowl of an electric mixer, beat the sugar, vanilla, pumpkin puree and eggs until smooth. As the wet ingredients mix together, whisk the flour, baking powder, baking soda, ginger, cinnamon and salt together in a separate bowl. Add to the wet ingredients and mix until just combined.
Scoop batter into the muffin tin, filling each cup about 3/4 of the way. Sprinkle about 2-3 tablespoons of the chilled streusel topping over each one, pressing the crumbles lightly into the batter if they fall off. Grate fresh nutmeg over each muffin cup, then bake in a preheated oven at 350 degrees for 25-30 minutes. Rotate the baking sheet halfway through baking. Remove from oven and allow to cool a few minutes before removing from the tin.