1. Heat waffle iron and lightly coat with non-stick spray.In a large bowl place whisk together butter, sugars, egg and vanilla extract until well blended.
2. Combine the flour, baking soda and lime zest; gradually whisk into wet mixture. Fold in mashed blueberries
3. Drop 1 heaping tablespoon of batter (or use a cookie scoop) onto waffle iron. Close the waffle iron and cook for 1-2 minutes or until golden brown.
4. Remove and transfer waffle cookies to wire rack, cool completely before glazing. Once cooled, dip waffle cookies in glaze and let dry.To make glaze:In a small sauce pan over medium high heat cook blueberries and water until mixture resembles thick syrup; strain blueberries.
5. Combine blueberry syrup with confectioners' sugar and whisk until smooth.
6. Add lime juice and whisk to combine.