Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan.

In a medium bowl, mix together the all-purpose flour, brown sugar, cinnamon, and softened butter until well combined. Press the mixture into the bottom of the prepared pan.

Bake the crust for 10–12 minutes, or until lightly golden. Remove from the oven and let it cool slightly.

In a mixing bowl, beat the cream cheese until smooth. Add additional flour, granulated sugar, and eggs, mixing until combined. Fold in 6 ounces of semisweet chocolate chips.

Pour the creamy chocolate mixture over the pre-baked crust and spread it evenly.

Return the pan to the oven and bake for 20–25 minutes, or until the topping is set. Let cool at room temperature.

Melt the remaining 6 ounces of semisweet chocolate chips and spread over the cooled bars. Sprinkle with toasted pecans or walnuts.

Allow the bars to set for about 30 minutes, then cut into squares and serve.