Get prepped. Heat the oven to 350°F (175°C). Line an 8x8-inch pan with parchment paper, leaving an overhang for easy removal. Melt ½ cup butter and measure out all remaining ingredients.
Make the crust. Stir 1 ½ cups graham cracker crumbs and melted butter together until evenly coated. Press firmly into the bottom of the prepared pan, making sure the crust reaches the corners. Bake for 8 to 10 minutes, just until set. This quick bake helps prevent a soggy bottom and gives the bars structure.
Layer the filling. Sprinkle 1 cup semisweet chocolate chips evenly over the warm crust. Add 1 cup shredded coconut in an even layer, followed by ½ cup chopped pecans. Slowly drizzle an entire 14 oz can sweetened condensed milk over the top, working close to the edges so it soaks through evenly.
Bake. Return the pan to the oven and bake for 25 to 30 minutes, until the top is lightly golden and the center looks set, not wet or jiggly.
Cool and slice. Let the bars cool completely in the pan. For the cleanest slices, chill for at least 1 hour before cutting. Lift out using the parchment and slice into 16 bars.
Notes
Press the crust firmly into the pan.
Pre-bake the crust before adding the layers.
Drizzle the condensed milk evenly, including the edges.
Cool completely, then chill for the cleanest slices.