Preheat oven to 350. Grease a 12 muffin cup tin. Be sure and spray very generously, if you don't, they will stick. Using Bakers Joy always works for me.
In a bowl, stir brown sugar, flour and pecans together. In a separate bowl, beat together the butter and eggs. Stir the wet mixture into the dry ingredients and combine.
Fill each muffin cup 2/3 full. Bake for 15-17 minutes. Take a knife and run it around the edge of each muffin before removing.
Notes
This recipe does not have any baking powder or baking soda. The recipe is correct as written.