To make the mix, pour the flour, sugar, baking powder, and salt into a 2-quart jar. You may need to pack it down some to fit.
Place the top on the jar and it will keep at room temperature for up to 3 months.
To make the cake, preheat the oven to 350°F. Spray a 9x13 baking dish with baking spray and set aside.
Place the cake mix into a large bowl and stir together, set aside.
Whip the butter until smooth in the bowl of a stand mixer with the paddle attachment or in a large bowl with an electric hand mixer.
Add the eggs one at a time, mixing the first one in fully before adding the next.
Add the milk and vanilla and stir. The mixture may appear lumpy, but that’s okay.
Add the flour mixture into the bowl in 3 batches, fully mixing it in.
Pour the batter into the prepared baking dish, and smooth out the top.
Bake for 32-40 minutes until a toothpick inserted into the center comes out clean.
Allow to cool completely then add your favorite toppings!
Notes
Please refer to my FAQ’s (Frequently Asked Questions) and ingredient list above for other substitutions or for the answers to the most common questions.