Servings: 30 1 stick, 1/2 cup butter, softened at room temp 1/2 cup granulated sugar 1 egg, room temp 1/2 tsp baking soda 1/2 tsp white vinegar 2 cups + 2 Tbsp all-purpose flour 1 cup jam or thick preserves, I used strawberry spread from Costco Powdered sugar for dusting, optional
Cream together 1 stick of butter with 1/2 cup sugar and 1 egg. Stir together 1/2 tsp baking soda with 1/2 tsp vinegar. Once it fizzes, pour over your batter and mix until well combined.
Blend in 2 cups + 2 Tbsp flour. P.S. I measured flour by fluffing it up with a spoon then spooning it into the measuring cup and scraping off the top for exact measurements.
Freeze 1/3 of the dough for 45 min to 1 hr. Place remaining 2/3 of dough onto a large sheet of parchment paper, sprinkle lightly with flour and roll into a 9x13" rectangle. Transfer rolled dough with parchment paper onto a jelly roll pan (rimmed cookie sheet; I used a 10x15"). Cover rolled dough with plastic wrap and leave at room temp until remaining dough is ready for grating.
Spread 1 cup of strawberry preserves over the top (or your favorite preserves - pick one with a little bit of sour/tartness). Grate the frozen piece of dough evenly over the top of your preserves.
Bake at 350 for 25 min or until top is golden. When cooled, dust with powdered sugar if desired and cut into square cookies.