Step 1: Preheat the Oven

1. Preheat your oven to 350°F (175°C). This ensures that your cookies bake evenly.

Step 2: Prepare Baking Sheets

2. Line two baking sheets with parchment paper or silicone baking mats. This prevents the cookies from sticking and makes for easy cleanup.

Step 3: Make the Cookie Dough

3. Cream the Butter and Sugar:

   • In a large mixing bowl, use an electric mixer to cream together the softened butter and confectioner's sugar until light and fluffy. This should take about 2-3 minutes.

4. Add Vanilla Extract:

   • Mix in 1 teaspoon of vanilla extract until fully combined.

5. Combine Dry Ingredients:

   • In a separate bowl, whisk together 1 3/4 cups of all-purpose flour and 1/4 teaspoon of salt. If using, you can also add 1 teaspoon of lemon zest to this mixture for added flavor.

6. Mix Dry Ingredients with Wet:

   • Gradually add the dry flour mixture to the butter and sugar mixture, mixing until just combined. Do not overmix; the dough should be soft and slightly sticky.

7. Add Optional Ingredients:

   • If desired, fold in 1/2 cup of chopped nuts and 1 egg yolk at this stage for extra richness and texture.

Step 4: Form Cookies

8. Shape the Cookies:

   • Using your hands, scoop out about 1 tablespoon of dough and roll it into a ball. Place it on the prepared baking sheet. Repeat until all the dough is used, spacing the balls about 2 inches apart.

9. Create Thumbprint Indentations:

   • Using your thumb or the back of a teaspoon, gently press down in the center of each ball to create a small indentation. Ensure the base is thick enough to hold the jam without breaking.

Step 5: Fill with Jam

10. Add the Jam:
    • Spoon about 1 teaspoon of raspberry jam into each thumbprint indentation. Be careful not to overfill, as it can spill out during baking.

Step 6: Optional Rolling

11. Roll in Sugar (Optional):
    • If you’re using the optional granulated sugar, roll the edges of each cookie ball in 1/4 cup of granulated sugar before baking.

Step 7: Bake the Cookies

12. Bake:
    • Place the baking sheets in the preheated oven and bake for 12-15 minutes, or until the edges are lightly golden. The jam will bubble slightly, which is normal.

Step 8: Cool the Cookies

13. Cool:
    • Remove the cookies from the oven and let them cool on the baking sheet for about 5 minutes. Then, transfer them to a wire rack to cool completely.

Step 9: Serve and Store

14. Serve and Store:
    • Enjoy your Rustic Raspberry Thumbprint Cookies fresh! Store any leftovers in an airtight container at room temperature for up to one week.

These detailed instructions will guide you through making flavorful and healthy Rustic Raspberry Thumbprint Cookies, perfect for holiday gatherings or a sweet treat anytime! Enjoy!