Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish with butter or non-stick spray.

In a large mixing bowl, cream together ½ cup of butter, 1 cup of brown sugar, and ½ cup of granulated sugar for 1-2 minutes.

Beat in 2 whole eggs, 1 egg yolk, and 2 teaspoons of vanilla extract until fully combined. Gradually incorporate 2 cups of self-rising flour.

Pour about two-thirds of the dough mixture into the greased baking dish and smooth it out evenly.

In a small bowl, whisk 1 cup of grape jelly until smooth and spreadable, then carefully spread it over the dough layer.

Drop spoonfuls of the remaining dough over the jelly layer and gently spread to cover most of the jelly.

Bake for about 40 minutes or until the top turns golden brown and a toothpick comes out clean.

Allow to cool at room temperature for at least 30 minutes before cutting into squares or rectangles.