Cake in a Jar Recipe

Directions

1. Warm up your oven to 350°F. Butter or shortening a 9x13 or 7x11 inch jelly roll pan, then line it with parchment. Apply another layer of grease and dust with flour, then put it aside.
2. In a medium bowl, combine the flour, cornstarch, baking powder, and salt using a whisk.
3. With a stand mixer fitted with the paddle attachment or a hand mixer in a large bowl, beat the butter and sugar together for 3–4 minutes until the mixture turns pale, light, and fluffy.
4. Drop in the egg whites one at a time, making sure each is fully mixed in before adding the next. Then stir in the canola oil and vanilla.
5. Turn the mixer to low and add the dry ingredients in three parts and the milk in two parts, beginning and finishing with the dry mixture.
6. Blend only until the flour disappears—overmixing leads to a dry, tough cake.
7. Carefully fold in the rainbow sprinkles with a spatula.
8. Transfer the batter to your prepared pan and bake for 8 to 12 minutes. Test by inserting a toothpick into the center; when it emerges clean, the cake is done. Allow it to cool fully.
9. Using a stand mixer or hand mixer in a large bowl, beat the stick of butter for 3–4 minutes until it becomes creamy and pale yellow.
10. Add the powdered sugar and vanilla, then mix on low speed until the mixture appears crumbly.
11. Increase the speed and beat for another 3–4 minutes until the frosting is light and fluffy.
12. Add milk or cream 1 tablespoon at a time, beating until you reach your preferred consistency. Transfer the frosting to a piping bag fitted with a large tip.
13. After the cake is cool, use round cookie cutters to stamp out circles matching the diameter of your jars. Keep in mind any taper—jars may be narrower or wider at the top—and cut circles accordingly.
14. For a more rustic presentation, simply break the cake into chunks and layer them in the jar. This also works well for leftover cake scraps.
15. Place your first cake layer in the jar. Pipe or spoon a layer of frosting on top. After each layer, wipe the jar's interior with a paper towel or cloth to keep it clean.
16. Optionally, add sprinkles, crushed cookies, caramel, or other toppings. Repeat the layers—cake, frosting, toppings—until you reach the top of the jar.
17. Finish by adding any final toppings to the top layer, then seal the jar. Your cake in a jar is ready to serve, give as a gift, or store.