In a food processor, process bread slices to fine crumbs. Add sugar and cinnamon and process until uniform in color and well mixed. Set aside in a bowl.

Heat oven to 350°F. Line two baking sheets with parchment paper.

In a medium bowl, Sift flour, cornstarch, baking powder, salt and cinnamon together. Whisk until blended.

In bowl of a stand mixer, beat butter, sugar and brown sugar for 3 to 5 minutes or until light and smooth.

Add egg and mix well. Add sour cream and maple extract. Blend well.

Add flour mixture to butter mixture and blend on low speed just until dry ingredients are moistened.

Using a cookie scoop (2 ½ to 3 tablespoon size) drop 1 dough ball into the bowl of cinnamon sugar crumbs. Roll the cookie ball around until coated with crumbs. Transfer to prepared baking sheet.

Repeat with remaining cookie dough and crumbs spacing cookies 2-inches apart on cookie sheet. You should have about 22 cookies.

Bake for 13 to 15 minutes or until puffed and golden brown around the edges.

Slide cookies on parchment to a wire rack to cool completely.