Preheat oven to 350F (175C).

In a bowl, combine flour, 1 cup brown sugar, and softened butter.

Mix until the mixture resembles fine crumbs.

Press the mixture onto the bottom of an ungreased 13x9-inch baking pan.

Spread pecan halves evenly over the unbaked crust.

In a saucepan, combine remaining butter and brown sugar.

Cook over medium heat, stirring constantly, until the mixture boils.

Boil for 1 minute, stirring constantly.

Pour the caramel mixture evenly over the pecans and crust.

Bake for 18-22 minutes, until the caramel layer is bubbly.

Remove from the oven.

Immediately sprinkle chocolate chips over the hot caramel.

Allow the chips to melt slightly.

Swirl the melted chips to create a marbled effect, leaving some whole.

Let cool completely before cutting into bars.