In a food processor, pulse the almonds and cornstarch until the almonds are finely ground.

Using a stand mixer with a large bowl attached, beat the butter and powdered sugar until smooth. Once incorporated, increase the speed to high. Beat until light and fluffy, and scrape down the sides with a rubber spatula.

Add the vanilla, salt and vegetable oil. Beat on medium speed until incorporated. Scrape down the sides of the bowl with a rubber spatula.

Turn the mixer on low, and slowly alternate adding the almond mixture and flour. Mix until combined, then scrape down the sides with a rubber spatula.

Divide the dough into two even pieces. Place each onto a separate strip of plastic wrap, and wrap tightly.

Refrigerate dough for at least 2 hours.

Preheat the oven to 325°F. Line two baking sheets with parchment paper, and set aside.

Sprinkle flour on a flat, dry surface.

Remove one round of dough from its plastic wrap, and roll with a rolling pin until about 1/4" thick.

Use a floured cookie cutter to cut out your cookies. For half the cookies, you'll leave the cookie whole while the other half, you will cut out the centers of the cookies with another prepared cookie cutter. (I used snowflake shapes, but you can use whatever shape you have on hand as long as the cutter that is used for the centers is smaller than the size of the cookie cutter used to create the main cookie shapes.)

Transfer the cookies a prepared baking sheet, setting them about 1" apart from one another. They should hold their shape when they bake.

Repeat this process with the second round of dough until all cookies have been formed and transferred to the baking sheets.

Bake for 17-20 minutes, or until the edges have turned golden brown.

Transfer the cookies to a wire rack for cooling, and let cool completely.

Sprinkle additional powdered sugar on top of the cooled cookies with cut-out centers.

In a small bowl, heat the jam until slightly warm, and stir until smooth.

Spread the top of the whole cookies with a tablespoon of jam.

Place the cookies with the cut-out centers on top of them to form the tops of the sandwich cookies.

Enjoy with a glass of milk!