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Preheat the oven to 350°F. Lightly grease 12 to 14 standard muffin cups. You'll use the larger number of cups if you include the full amount of all three add-ins: chocolate chips, walnuts, and cinnamon chips.
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In a medium-sized mixing bowl or the bowl of your stand mixer, beat together the butter and sugar till smooth.
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Beat in the mashed banana, then the egg, flavorings, and milk.
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Add the baking powder, baking soda, salt, and flours, stirring till smooth; if the mixture has a lot of lumps, beat at a higher speed until they've nearly disappeared.
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Stir in the chocolate chips, walnuts, and cinnamon chips.
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Heap the thick batter into the prepared muffin cups, mounding them quite full; a muffin scoop works well here. Sprinkle the tops of the muffins with coarse white sparkling sugar, if desired.
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Bake the muffins for 20 to 23 minutes, until a cake tester inserted into the center of one of the middle muffins in the pan comes out clean.
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Remove the muffins from the oven, and tilt them in the pan to cool a bit; this will prevent their bottoms from becoming soggy. As soon as you can safely handle them, transfer the muffins to a rack to cool completely.
