Combine brownie mix, egg, vegetable oil, and strong coffee into a large bowl. Mix well.
3. Step
Pour batter into a parchment lined 10x15-inch (25x38 cm) baking sheet.
4. Step
Bake for about 10 minutes.
5. Step
While the brownie is baking and cooling, mix mascarpone cheese, espresso powder, and vanilla extract together in a bowl until smooth.
6. Step
In a separate bowl, whip the heavy cream and gradually add in powdered sugar.
7. Step
When the cream is whipped, add to the mascarpone cheese mixture and gently fold until homogenous.
8. Step
Take the brownie out from the baking sheet put on a flat surface, then use either a mason jar lid or a cookie cutter to cut out as many circles as you can.
9. Step
To assemble the tiramisu, alternate the cream and brownie, starting with the cream.
10. Step
Chill tiramisu in the fridge for an hour.
11. Step
To serve, dust with cocoa powder and/or espresso powder.
