Preheat oven to 180°C (350°F).
Blend oil, carrots, eggs, and sugar until completely smooth.
Pour into a large bowl. Gradually fold in flour, then baking powder.
Pour into a greased 9x13 pan. Bake 25 to 30 minutes until a toothpick comes out clean.
Cool completely before making brigadeiro.
Combine all brigadeiro ingredients in a saucepan over medium heat. Stir continuously until melted and thickened, about 8 to 12 minutes. It should be thick but pourable.
Flip cooled cake onto a wire rack over a tray. Pour brigadeiro over the top and smooth.
Let set 10 minutes, then transfer to a plate to slice.
