Preheat oven to 350. Line an 8Ã—8 pan with parchment (or aluminum foil). Combine sugar, flour, cocoa, baking powder, and salt. In a separate bowl, whisk oil, eggs, and vanilla. Add flour mixture and stir gently to combine Stir gently to combine. Spoon into prepared baking pan. Bake until toothpick comes out clean, about 25 to 30 minutes. Cool completely before proceeding.