Set your oven to 350°F (or 325°F if you're using a glass baking dish).

Place the stick of butter directly in a 13x9-inch baking pan. Slide it into the oven for about 5 minutes, just until the butter is fully melted.

Remove the pan from the oven and sprinkle the graham cracker crumbs evenly over the melted butter. Stir gently to coat the crumbs in the butter, then press the mixture into a flat, even crust.

Pour the sweetened condensed milk evenly over the crust, using a spatula to spread it out if needed.

Sprinkle the coconut flakes across the top, followed by the chocolate chips and butterscotch chips.

Bake for 27–30 minutes, or until the top is golden brown and bubbly.

Allow the bars to cool at room temperature for at least 1 hour. For faster cooling, pop the pan in the refrigerator. This helps the bars firm up for easier cutting.

Cut into 12 large bars or 24 smaller squares. Sprinkle with a pinch of flaky sea salt, if desired, for an extra flavor boost. Store loosely covered at room temperature.