01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, ensuring paper overhangs edges for easy removal.
02 - Combine flour, melted butter, sugar, and salt in a bowl. Mix until crumbly dough forms. Press mixture evenly into the bottom of the prepared pan.
03 - Bake crust for 10 minutes until lightly set. Remove from oven and set aside.
04 - Combine semi-sweet chocolate chips and sweetened condensed milk in a small saucepan. Cook over low heat, stirring constantly until smooth and fully melted.
05 - Spread chocolate mixture evenly over the pre-baked crust. Sprinkle with chopped nuts, mini chocolate chips, and coconut if desired.
06 - Return pan to oven and bake for 15 minutes until edges are set and center appears firm.
07 - Let bars cool completely in the pan. Lift out using parchment paper overhang and cut into 12 equal squares.