Preparation

• Preheat the oven to 350 degrees F (175 degrees C).
• Make the crust: Combine flour, brown sugar, and softened butter in a large mixer bowl. Beat at medium speed until mixture resembles fine crumbs, 2 to 3 minutes. Transfer mixture to an ungreased 13x9-inch baking pan. Pat evenly over the bottom to form a crust.
• Make the turtle layer: Combine butter and brown sugar in small saucepan over medium heat. Cook and stir until bubbles form over the entire surface. Continue to cook, stirring constantly, 30 to 60 seconds more. Remove from the heat.
• Sprinkle pecans evenly over the crust, then pour hot brown sugar mixture over top.
• Bake in the preheated oven until the entire surface is bubbly, 18 to 20 minutes.
• Remove from the oven and set on a wire rack. Immediately sprinkle chocolate chips evenly over the surface and let stand until chocolate melts, 2 to 3 minutes. Use a knife or small spatula to swirl the melted chocolate slightly.
• Let sit until completely cooled, about 30 minutes. Use a sharp knife to cut into 48 bars.