Adjust oven rack to middle position and heat oven to 350 degrees. Line 13 by 9-inch baking pan with foil, allowing excess to overhang pan edges. Generously coat foil with cooking spray. Process toffee bits in food processor to fine powder. Add graham crackers and process to fine crumbs. Transfer mixture to bowl and stir in butter. Press mixture firmly into prepared baking pan. Bake until beginning to brown, about 10 minutes.
Remove pan from oven, sprinkle crust with milk chocolate, and allow chocolate to soften, about 2 minutes. Using spatula, smooth chocolate into even layer. Scatter Rice Krispies over chocolate, pressing to adhere. Add layers of pecans, chocolate chips, and coconut, in that order, pressing each layer to adhere. Combine condensed milk and vanilla in small bowl and pour over coconut.
Bake until golden brown, 25 to 30 minutes. Cool on wire rack, about 2 hours. Using foil overhang, lift from pan and cut into 24 squares. (The bars can be stored in airtight container for up to 3 days.).