In a large mixing bowl, combine the yellow cake mix, melted butter, 2 eggs, and 1 teaspoon of vanilla extract. Stir by hand with a spatula until everything is well mixed. The mixture will be thick, like dough.

Spread the mixture evenly into the bottom of your greased 9×13 inch baking dish, pressing it down to cover all corners. It’s the crust, so it doesn’t need to be perfect, just even.

In another bowl, use an electric mixer to blend the softened cream cheese, 2 eggs, and 1 teaspoon of vanilla extract until smooth.

Add the fresh lemon zest and mix it in. Slowly add the powdered sugar, one cup at a time, mixing well after each addition. Pause to scrape down the sides of the bowl to make sure everything is blended.

Pour the cream cheese topping over the crust in the baking dish. Use a spatula to spread it evenly, being careful not to disturb the crust below.

Preheat your oven to 350°F (175°C). Place the assembled cake in the oven and bake for 30-35 minutes. The top should be golden and slightly puffed up, with the center still a bit jiggly-that’s what makes it gooey!

Let the cake cool completely in the pan on a cooling rack, about 1 hour. Once cooled, dust the top with powdered sugar. Cut the cake into squares or bars and serve.