Preheat your oven to 350°F (180°C). Grease and flour a 9x9-inch square baking pan.

In a medium mixing bowl, whisk together the flour, sugar, baking powder, cocoa powder, and salt.

In a large mixing bowl, beat together the vegetable oil, eggs, milk, and vanilla extract. Gradually add the dry ingredients to the wet ingredients and mix until well combined.

Pour the batter into the prepared baking pan and smooth the top with a spatula. Tap the pan gently on the counter to release any air bubbles.

Bake the cake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

Serve the chocolate cake warm, or store it in an airtight container at room temperature for up to 3 days.