Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, then line the bottoms with parchment paper. Set aside.

In a large bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and salt. Set aside.

In another large bowl, using an electric mixer, cream together the softened unsalted butter until light and fluffy (about 2-3 minutes).

Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed.

In a separate small bowl, combine the whole milk, vanilla extract, pistachio extract, and green food coloring (if using).

Gradually add the dry ingredients to the butter mixture in three additions, alternating with the milk mixture in two additions, beginning and ending with the dry ingredients. Mix on low speed until just combined, being careful not to overmix.

Gently fold in the finely ground pistachios.

Divide the batter evenly between the two prepared cake pans. Bake for 28-32 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cakes cool in the pans for 10-15 minutes before inverting them onto a wire rack to cool completely. This is crucial for assembly, ensure they are fully cooled.

In a large bowl, beat the softened cream cheese and powdered sugar with an electric mixer until smooth and creamy.

Stir in the pistachio butter/paste (or ground pistachios and oil), vanilla extract, and pinch of salt until well combined.

In a separate cold bowl, whip the very cold heavy cream on medium-high speed until stiff peaks form.

Gently fold the whipped cream into the cream cheese mixture until no streaks remain. Cover and refrigerate until ready to use.

In a large bowl, cream together the softened unsalted butter and softened cream cheese with an electric mixer until smooth and lump-free (about 3-4 minutes).

Gradually add the sifted powdered sugar, 1 cup at a time, mixing on low speed until incorporated, then increasing to medium speed until smooth. Scrape down the bowl frequently.

Beat in the vanilla extract and pinch of salt. If the frosting is too thick, add heavy cream 1 tablespoon at a time until desired consistency is reached.

Once the cake layers are completely cooled, use a serrated knife to level the tops if necessary, creating flat surfaces.

Place one cake layer on your desired serving plate or cake stand. If using, pipe a dam of cream cheese frosting around the edge of the first cake layer. This will prevent the filling from oozing out.

Evenly spread the chilled Pistachio Cream Filling inside the frosting dam.

Carefully place the second cake layer on top, pressing down gently to secure it.

Apply a thin layer of cream cheese frosting all over the cake (top and sides) to create a crumb coat. This traps any loose crumbs. Chill the cake in the refrigerator for 15-20 minutes to set the crumb coat.

Once chilled, apply the remaining cream cheese frosting to the top and sides of the cake, smoothing it with an offset spatula or palette knife.

Garnish the top of the cake with chopped pistachios. You can also press some onto the sides if desired.

Refrigerate the cake for at least 30 minutes before slicing and serving to allow the filling and frosting to set properly. Enjoy!