Coat mini-muffin tins with nonstick cooking spray.
With your electric mixer beat the butter and sugar for 5 minutes until soft, fluffy and lighter in color. Beat in the egg until just mixed in. Add the diced strawberries and mix in.
Sift together the flour, baking powder, and salt. Stir half of the dry ingredients into the batter.
Stir in the buttermilk. Continue mixing in the remaining dry ingredients until well combined and batter is smooth.
Fill mini muffin tins with 1 1/2 tablespoons of batter (about 3/4ths full). Bake for 14-15 minutes until a toothpick comes out clean when inserted. Set aside to cool.
In a small bowl mash the strawberry, add lemon juice and powdered sugar. Stir to mix thoroughly.
When the muffins are just cool enough to handle, dip the tops into the glaze (See Note 2).Place on a rack to cool completely.
1. I used King Arthur White Whole Wheat Flour when making these because it's lighter in color, but regular whole wheat flour works just as well. 2. Feel free to cut the glaze recipe in half, but I ended up needing a little more than that. You can save the extra glaze for another use or drizzle on pancakes or waffles.