Preheat oven to 400 degrees F. In a mixing bowl whisk together flour, sugar, baking powder, baking soda and salt.
In a separate mixing bowl whisk together buttermilk, eggs and melted butter. While whisking, pour buttermilk mixture into flour mixture and mix just until combined (batter will be slightly lumpy). Allow batter to rest 2 minutes.
Spray each well of two 24 mini muffin cup pans with non-stick cooking spray. Fill each muffin well about 2/3 full (a heaping Tbsp into each. I have a 1 1/2 Tbsp cookie scoop and filled it nearly full). If adding toppings, add 4 blueberries in each, or 1 raspberry, or scant 1 tsp mini chocolate chips. If doing cinnamon sugar topping, once the plain muffins are done, brush tops lightly with melted butter, remove from pan and immediately roll in cinnamon sugar (these taste like churros!).
Bake in preheated oven 10 - 12 minutes.*
Cool one minute then invert onto a wire rack (for the blueberry version you may need to run a sharp knife around edges to loosen). Serve immediately with maple syrup.
Notes
*These pancake muffins won't color much while baking (or maybe the top element in my oven is slacking), but they should be nice and puffed and centers shouldn't be wet. You can break one open to test.
Nutrition estimate doesn't include mix-ins or toppings.