This muffin batter will support the addition of berries, nuts,grains, seeds, pastes; such as peanut butter, pumpkin etc. Add your choice of spices to taste. Whole wheat Pastry flour may be substituted for all purpose flour.
Sift together flour, baking powder, salt and spices if using, into bowl and whisk together until well blended. Add berries and nuts if using at this time to flour mixture and stir to coat; set aside.
In separate bowl whisk eggs until very creamy and add the sugar in several additions whisking vigorously until thick. Add melted butter in 2 steps whisking again until well mixed. Add sour cream and optional pastes in several additions and again whisk vigorously till well combined.
With a large rubber spatula fold flour mixture into batter until just incorporated, you will see some small spots of flour, do not overmix. Batter may be refrigerated over night or for several hours, dough will develop more flavor.
Bake at 350°F for 25 to 30 minutes until light golden brown and toothpick test comes out clean. Suggest preheat oven at least 30 minutes to get maximum burst. Oven rack middle of oven.