Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking dish.

In a large mixing bowl, combine 1 cup of softened unsalted butter with 1 cup of brown sugar and ½ cup of granulated sugar. Beat until smooth and creamy.

Add 2 large eggs and 1 teaspoon of vanilla extract to the mixture. Beat until well combined.

Gradually sift in 2 cups of self-rising flour and fold it gently into the mixture until incorporated.

Pour approximately two-thirds of the dough into the prepared baking dish and spread it evenly.

Take 1 cup of grape jelly and spread it over the layer of dough, leaving some edges exposed.

Spoon small dollops of the remaining dough on top of the jelly layer.

Bake for about 40 minutes, until the edges are golden brown and a toothpick comes out mostly clean.

Let the bars cool in the pan for at least 15-20 minutes before cutting them into squares.