Start by heating your oven to 350°F (175°C). While it’s warming up, give your 9x13 pan a generous spray with non-stick spray—this little trick makes sure your cake slips right out when it’s done, no sticking drama.

Break the chocolate into chunks and add it to a microwave-proof bowl with the butter and oil. Microwave in short bursts of 20 seconds, stirring after each one until everything’s melted into a silky, shiny mix. The smell alone is worth the wait!

In a large bowl, whisk together the cocoa powder, both sugars, flour, baking soda, baking powder, and salt. Make sure it’s well blended so every forkful has that perfect balance.

In a separate bowl, lightly beat your eggs. Mix in the sour cream, vanilla, and milk until smooth. This combo is what keeps the cake moist and tender, so don’t skip the smooth part.

Incorporate the melted chocolate mixture into the wet ingredients, stirring until smooth and uniform. Slowly add the dry ingredients, folding gently just until the batter is mixed through.

Pour in the freshly brewed coffee and let the batter rest for a minute to let the cocoa bloom and flavors deepen. Stir gently, then pour your thin, luscious batter into the pan and smooth the top.

Pop it into the oven and bake for around 42 minutes. Start checking at 37 minutes by doing the toothpick test.

While your cake cools, whip up the frosting. Beat softened butter until creamy, then gradually add powdered sugar, a splash of heavy cream (one spoonful at a time), and vanilla.

Mix on low until everything is just combined, then fold in the melted dark chocolate. Crank the mixer for a couple of minutes until the frosting is light and fluffy.

Spread that heavenly frosting all over the cooled cake, slice it up, and dig in! Trust me, every bite is pure chocolate bliss.