Heat a large skillet or griddle over medium heat.In a medium bowl, combine the flour, sugar, baking powder, baking soda, and salt. Whisk to combine.In a small bowl, mix together the buttermilk, eggs, oil and vanilla.Stir the wet ingredients into the dry ingredients until combined but still slightly lumpy.If you're making one color and flavor of pancakes, stir the ¼ cup of gelatin powder into the pancake mix.If you're making rainbow pancakes, place ½ cup of batter into 6 separate bowls. Stir 2 tsp of one flavor of gelatin powder into one bowl. Repeat with the remaining flavors and colors.Spray your cooking surface with nonstick cooking spray and place ¼ cup of the pancake batter in the pan.Cook for 3 minutes per side or until cooked through. Repeat with remaining pancakes.Beat together the butter and vanilla with an electric mixer until creamy. Gradually beat in the salt and powdered sugar until well combined. Add the heavy cream, a little at at time, to reach the consistency you desire.Spread frosting on the pancakes and serve.