1. Preheat the Oven: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat to prevent the cookies from sticking.
2. Make the Cookie Dough: In a large bowl, cream together the softened butter and powdered sugar until smooth and fluffy, about 3 minutes. This will create the base for a tender shortbread. Add the almond extract, vanilla extract, and salt, mixing until combined.
3. Add the Flour: Gradually add the all-purpose flour, stirring until just incorporated. The dough should be soft but firm enough to hold its shape. If the dough is too soft, refrigerate it for about 10 minutes to make it easier to work with.
4. Shape the Cookies: Roll the dough into 1-inch balls and place them about 2 inches apart on the prepared baking sheet. Use your thumb or the back of a spoon to make an indentation in the center of each cookie.
5. Fill with Jam: Spoon about 1/2 teaspoon of raspberry jam into each indentation, being careful not to overfill.
6. Optional Garnish: If using sliced almonds, gently press a few slices around the edges of the cookie for added crunch and flavor.
7. Bake the Cookies: Bake for 12-15 minutes, or until the edges are lightly golden. Be careful not to overbake them, as shortbread can dry out quickly.
8. Cool and Serve: Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.

Enjoy these Raspberry Almond Shortbread Thumbprint Cookies as a delightful treat for any occasion!