Prepare the Crust:

1. In a small bowl, whisk together the buttermilk, egg yolks, and vanilla. Set aside.

2. In a food processor, pulse the flour, powdered sugar, and salt to combine.

3. Add the cold butter and pulse until the mixture resembles pea-sized crumbs.

4. While the processor is running, pour in the wet ingredients and mix until the dough starts coming together.

5. Transfer the dough onto plastic wrap, form into a disc, and wrap tightly. Refrigerate for 1 hour or freeze for 15-20 minutes.

6. Preheat oven to 375°F (190°C).

7. Press the chilled dough into a greased 8×8″ pan, covering the bottom and slightly up the sides.

8. Wrap the pan in plastic wrap and freeze for 20 minutes.

9. Remove the wrap and bake for 20-25 minutes until set but not golden.

10. Lower oven temperature to 325°F (163°C).

Prepare the Filling:

1. In a small bowl, gently mix the raspberries with 1/4 cup sugar. Let sit while making the filling.

2. In a separate bowl, whisk together the eggs, remaining 1 ½ cups sugar, flour, and lemon zest until pale yellow.

3. Stir in the lemon juice until combined.

Assemble & Bake:

1. Scatter the raspberries over the warm crust.

2. Pour any juices from the raspberries into the lemon filling, whisk again, then pour over the crust.

3. Bake at 325°F for 20-30 minutes, until the center is set and no longer jiggles.

4. Let cool completely before slicing.

5. Serve immediately or wrap and refrigerate overnight for best flavor.