In a medium bowl, combine flour, baking powder, and salt. Prepare flax egg by mixing ground flax seed (flaxseed meal) and 3 TBS water. Set aside to gel. 

In a large bowl or stand mixer, cream together butter, granulated sugar, vanilla extract, and optional almond extract. Beat until light and fluffy. Slowly add in dry mixture, mixing until just combined. 

Place the dough between two sheets of parchment paper (or silicone mats) and roll until ¼ inch thick. Keeping flat, place the dough in the fridge to chill for 30 minutes or in the freezer to chill for 15 minutes. It will be much easier to punch out shapes this way. 

Preheat the oven to 350 degrees F. Using any cookie cutter shape (I used a star), cut out as many cookies as possible. Set each cookie aside, and re-roll scraps to continue maximizing the number of cookies you are able to produce.

Once all dough is punched out, use a smaller cutout (I used a bottle) to punch a hole in HALF of the star shapes. So, if you were able to make 30 star cookies, punch holes in 15 of them. Feel free to re-roll the punched out portions of the cookies to produce more (or just bake them separately, they will still taste good). If your dough ever gets too warm to punch easily, add it back to chill for a few minutes before proceeding. 

Place all cookies (whole and punched) on two lined baking sheets and bake for 9-11 minutes, until lightly golden. Watch the edges for burning. Remove from the oven and let cool. Once cool, place the cookies with the punch-outs on their own sheet tray. Using a sifter, shower powdered sugar on these cookies; they will serve as the tops of our linzer sandwiches.

Spoon ½ TBS jam onto the centers of the whole cookies. Carefully place each powdered- sugar-covered punched out cookie on top of the cookie with jam. Form a sandwich.