Line two 13x9 baking sheets with parchment paper.

In a medium bowl, whisk together flour, cornstarch, and salt. Set aside.

In a large bowl, cream together the butter with the sugars using a stand mixer or hand mixer on medium speed, increasing to medium high until lighter and creamy (2-3 minutes).

Scrape down the bowl and mix in the egg yolk, vanilla, and almond extract.

Set the mixer to low and slowly add the dry ingredients into the wet ingredients, scraping down the bowl as needed.

Using a 1 tablespoon sized dough scoop, make dough balls and roll them smoothly between your palms.

Place each dough ball 2 inches apart on the baking sheet. Gently press a heart shape into the top of each ball of dough with a pinky finger.

Chill the cookie sheets in the freezer for 30 minutes or in the refrigerator for 1 hour.

Preheat the oven to 375°F after removing the cookie sheets from the freezer.

Heat the raspberry jam in a small microwave safe bowl for 10-15 seconds until slightly runny.

Using a 1/4 teaspoon or a very small spoon, fill the heart indent to the brim with about 1/2 teaspoon of jam.

Bake each tray of cookies for 10-12 minutes until the edges just start to turn golden brown.

Let cookies cool on the baking sheet for 5 minutes, then transfer them to a cooling rack.