Precision in the kitchen is over-rated.
1 c fruit puree, yogurt, or mixture of wet ingredients
1/4 c ground flaxseed mixed into wet ingredients, or 1 egg
a few tbsp of canola oil
2 c flours of your choice. Sub grain flakes at the ratio of 1c flakes = 1/2 c flour
2 tsp baking powder
1/2 tsp baking soda if fruit is acidic, or if yogurt is used
about 1/4 c sugar, or 1/2 c if you like things sweet (or mix 2 tbsp (4 for sweet) honey into wet ingredients)
pinch salt, optional
spices as desired - cinnamon, cardamon, ginger - depending on fruit used
Nuts, coconut, chocolate chips, dried fruit if desired - about 1/2 cup
Mix wet ingredients, pour dry on top, gently mix together. If it seems too wet, add a bit more flour. Bake muffins about 18 minutes at 400F. Makes about 12 muffins.
This particular rendition obtained the approval of 5 children:
2 bananas, mashed thoroughly
about 1.5 c plain yogurt
3 tbsp canola oil
1/4 c flax meal
--- Mix above together, then pour on top:
about 2.5 c flour (mostly whole wheat)
about 1/4 c sugar
1 tbsp cinnamon
1 tbsp baking powder
1/2 tsp baking soda
Mix and bake as above. This made 16 standard muffins.