Use a paddle attachment in a bowl with a stand or hand-held mixer, and beat the butter with the maple sugar for about 60 seconds. Add the powdered sugar and beat until light and fluffy—this should take around two minutes.

Add in the maple syrup and maple extract, beating everything together until well combined.

In a separate bowl, whisk together the all-purpose flour, cornstarch, and salt. Gradually add this dry mixture into your mixing bowl while beating until the dough comes together.

Wrap your cookie dough in plastic wrap and chill it in the refrigerator for about 30 minutes.

Preheat your oven to 350°F (175°C) and line two cookie sheets with parchment paper.

On a lightly floured surface, roll out your chilled dough to about an eighth of an inch thick.

Using a maple leaf cookie cutter, press down firmly onto the rolled-out dough to create shapes.

Bake the Maple Leaf Cookies in your preheated oven for approximately eight to ten minutes until they are lightly golden brown around the edges.

Beat together butter, powdered sugar, maple syrup, vanilla extract, maple extract, and salt until smooth and creamy.

Spread a generous portion of filling onto one Maple Leaf Cookie and top it with another cookie.