In a large mixing bowl, beat 1 cup of unsalted butter and 3/4 cup of granulated sugar using an electric mixer on medium speed for about 3 minutes until light and fluffy.

Add 1 large egg and 1 teaspoon of vanilla extract to the creamed butter mixture. Mix on low speed until combined, about 1 minute.

In a separate bowl, whisk together 2 cups of all-purpose flour, 1/4 cup of powdered sugar, and 1/2 teaspoon of salt. Gradually add to wet ingredients while mixing on low speed until a soft dough forms.

Warm raspberry jam in the microwave for 15-20 seconds if using. Alternatively, puree 1 cup of fresh raspberries and strain for a smooth texture.

On a floured surface, roll out the dough into a rectangular shape about 1/4 inch thick. Spread the raspberry jam/puree evenly, leaving a half-inch border.

Roll the dough into a log from one side, wrap in plastic wrap, and refrigerate for at least 1 hour.

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.

Slice the chilled log into 1/4 inch rounds, place them on the baking sheet with 2 inches apart, and bake for 10-12 minutes until lightly golden.