mix flour, sugars, baking powder, soda, and salt together; set aside.
whisk egg yolks, buttermilk, 6 tbsp butter, and vanilla together; set aside.
separately, whisk egg whites until soft peaks form; set aside.
heat skillet or griddle over medium-high heat and melt about 1 tbsp evenly over cooking surface.
add flour mixture to egg-buttermilk mixture and mix until just blended. fold in egg whites. scoop 1/4 cup of batter onto hot skillet and cook pancakes 2-3 minutes, until they start to bubble on top. flip and cook 2 minutes more. remove from heat, keep warm while cooking the rest, and serve topped with strawberries, coconut, and bananas.
variations: try adding slices of fruit to pancakes just after initially scooping them onto the skillet, before flipping (berries, banana, mango, kiwi, pineapple) and also serve with warmed peanut butter as well as syrup.