In a small bowl, combine ¾ fresh cherries and 1 tablespoon flour. Stir together to coat cherries and set aside.
In a large bowl, combine 1 C flour, baking powder, salt, cinnamon and sugar. Stir together until well combined.
Crack the egg into a second smaller bowl. Whisk the egg until frothy. Add in oil, milk and vanilla. Whisk together until combined.
Pour wet ingredients into dry and fold together about 10 strokes. Add the walnuts and banana and continue to fold about 5-10 strokes more.
Scoop batter into muffin cups. Fill each cup to the top. Sprinkle more cherries, walnuts and coarse sugar on top of each muffin.
Bake in preheated oven for 2 minutes at 400, then reduce temperature to 375 degrees. Cook for additional 23-25 minutes, until tops spring back when gently poked.
Store in an airtight container in the refrigerator.