Preheat your oven to 350°F (175°C) and grease two 6- or 7-inch round cake pans with olive oil.

In a small bowl, combine your choice of milk with apple cider vinegar or lemon juice and let sit for about 5 minutes.

Pulse the ground pistachios along with the sugar in a food processor until the mixture resembles a fine meal, about 30 seconds.

In a bowl, whisk together the flour, baking powder, and salt. In another bowl, mix the buttermilk, olive oil, vanilla extract, and almond extract, then fold into the dry ingredients.

Divide the batter evenly between the prepared cake pans and smooth the tops. Bake for 25–30 minutes or until a toothpick comes out clean.

Let the cakes cool in the pans for 10–15 minutes, then turn out onto a wire rack to cool completely.

Beat room temperature butter in a mixing bowl until light and fluffy, then add blackberry preserves and powdered sugar, mixing until combined.

Once the cakes are completely cool, level the tops and assemble by placing one layer on a serving plate, spreading buttercream on top, and placing the second layer on top.

Garnish the top of your cake with fresh blackberries and a sprinkle of chopped pistachios.