Ultimate Chocolate Fudge Cake

Preheat your oven to 350°F and generously grease two 9-inch round cake pans with butter, then line the bottoms with parchment paper circles to prevent sticking.
In a large mixing bowl, whisk together 2 cups flour, 1 3/4 cups sugar, 3/4 cup cocoa powder, 2 teaspoons baking soda, 1 teaspoon baking powder, and 1 teaspoon salt until thoroughly combined and no lumps remain.
Add 2 eggs, 1 cup buttermilk, 1/2 cup vegetable oil, and 2 teaspoons vanilla to the dry ingredients, then beat with an electric mixer on medium speed for 2 minutes until the batter is smooth and slightly thickened.
Carefully pour 1 cup boiling water into the batter and mix on low speed until just incorporated; the batter will be thin but should have a uniform chocolate color throughout.
Divide the batter evenly between the prepared pans and bake for 30-35 minutes until a toothpick inserted in the center comes out clean with just a few moist crumbs attached.
Let the cakes cool in their pans for 15 minutes, then run a knife around the edges and invert onto a wire rack to cool completely before frosting, about 1 hour.
For the frosting, beat 1 cup softened butter with an electric mixer until creamy, then gradually add 4 cups sifted powdered sugar and beat on low speed until combined before increasing to high for 3 minutes until fluffy.
Add 1/2 cup milk and 1 teaspoon vanilla, mixing until smooth, then fold in 1/2 cup cooled melted chocolate until fully incorporated, creating a spreadable, glossy frosting.