Preheat the oven to 350 degrees and line two cookie sheets with parchment paper. Set aside.

In a medium-sized bowl, whisk together the flour, baking powder, and salt. Set aside.

In a separate, larger bowl, use an electric mixer to beat the butter and sugar together on low speed until light and creamy—about 2 minutes.

Scrape down the sides of the bowl then add in the eggs one at a time mixing between each addition. Add the vanilla.

Scrape down the sides and bottom of the bowl again then add in the dry ingredients and mix to combine until a nice, soft, dough forms.

Set the cookie dough aside then mix all of the brown sugar cinnamon filling ingredients together in a small bowl.

Scoop ¾ cups of dough per cookie. Divide this dough ball in half. Roll each ½ into a ball then flatten into a disc. Scoop about 2 ½ tsp. of the brown sugar cinnamon filling in the center of one disc then top with the other ½. Pinch the sides together to seal the edges tightly. Place each cookie onto the prepared cookie sheet 2" apart (they will spread slightly).

Bake for 11-12 minutes or until slightly golden brown on the edges. As soon as the cookies come out of the oven, use a ¼ cup measuring cup to press a circle into the center of each cookie. Do this gently and slowly to avoid cracking the edges of the cookie. Allow these cookies to sit on the pan for about 5 minutes after baking before transferring to a wire rack to cool completely.

Once the cookies have cooled completely, you can make the glaze. Mix all of the glaze ingredients together with a whisk. The glaze should be thin and smooth. It should form slow ribbons when lifted over the bowl. If it is too thin, add more confectioner's sugar. If it's too thick, add a few small drops of milk until you've reached the perfect consistency.

Allow the glaze in the center to set a bit for about 1 hour before serving. Enjoy!