Preheat your oven to 325°F (163°C). Grease an 8-inch round cake pan and line the bottom with parchment paper.
In a large bowl, whisk together flour, cocoa powder, baking soda, and salt until well combined.
Add granulated and brown sugars. Mix until everything looks like it belongs together.
Pour in the olive oil, water, vinegar, and vanilla extract. Whisk until you’ve got a smooth, glossy batter.
Pour the batter into the prepared pan and tap it gently on the counter to settle any bubbles.
Bake for 45–50 minutes or until a toothpick comes out clean-ish with a few crumbs (no wet batter!).
Let the cake cool in the pan for 10–15 minutes, then transfer it to a wire rack to cool completely.
Dust with powdered sugar if you like, or just dive in.