In a bowl, add 6 eggs, sugar, and a tablespoon of vanilla sugar (or use 1 tablespoon vanilla extract if you don't have vanilla sugar). Beat well until the mixture doubles in volume. Next, add the vegetable oil while continuing to beat. You can use an electric mixer or a whisk by hand.

Sift the flour into the bowl using a strainer, add the baking powder, and gently fold everything together until combined.

Grease a 13x9 inch (32x22 cm) baking pan with a little vegetable oil and spread it evenly. Pour the batter into the pan, scraping the bowl to get it all. Bake in a preheated oven at 350°F (180°C) for 35 to 40 minutes, with heat from top and bottom.

After baking, check if the cake is done by inserting a toothpick in the center—if it comes out clean, it's ready. If not, bake for 5 more minutes. Let the cake cool to room temperature. Once cooled, poke holes all over the cake with a toothpick so the tres leches sauce can soak in and the cake doesn't turn out dry.

To make the tres leches sauce, combine the evaporated milk, heavy cream, and sweetened condensed milk in a bowl and mix well. Pour the sauce over the cake a little at a time, letting it absorb before adding more. Cover with plastic wrap and refrigerate for at least 8 hours, or overnight for best results.

After at least 8 hours, place the cold heavy cream in a bowl, add the vanilla sugar (or vanilla extract) and powdered sugar, and whip until stiff peaks form.

Spread the whipped cream evenly over the cake, smoothing the top. Finally, sprinkle a little ground cinnamon on top and enjoy!