In a saucepan, melt the butter over low-med heat for at least 10 minutes until it bubbles and turns brown. Keep stirring it as it gets hot to prevent scorching the bottom of the pan. Skim off the foam and pour this browned butter (yes it will be absolutely brown)- into a bowl until ready to use.
Pre heat oven to 325 F
Spray muffin tins generously with Pam cooking spray and dust with flour, tapping out the excess.
Combine all dry ingredients (but not the brown sugars) in a bowl and whisk.
In a mixing bowl, combine the rest of the ingredients- pumpkin, sugars, eggs, and brown butter and turn on the mixer to med. Slowly add the dry ingredients continuously until combined.
Divide the batter among the muffin tin spots, and bake for 10 minutes. Set timer. TURN the pan 180 degrees and bake another ten minutes. TOTAL bake time= 20 minutes.
Take pan out and be SURE to set it on a wire rack to let it completely cool. If you try to pop the muffins out while hot they will fall apart. Yes I did.
Finish with a big dollop of icing, your choice. ;)