01 -
Preheat oven to 350°F. Line a 9×13 inch baking pan with parchment paper, leaving overhang for easy removal. Lightly spray parchment with cooking spray.
02 -
Combine graham cracker crumbs, melted butter, sugar, and salt in a large bowl until mixture resembles wet sand and holds when pressed. Fold in mini chocolate chips. Press firmly and evenly into the bottom of the prepared pan using the bottom of a measuring cup to compact.
03 -
Bake crust for 10-12 minutes until set and light golden around edges. Remove and cool for 5 minutes while preparing chocolate layer. Keep oven on.
04 -
In a microwave-safe bowl or double boiler, combine chocolate chips, sweetened condensed milk, and butter. Heat in 30-second intervals, stirring until smooth and melted. Stir in vanilla and salt until glossy and thick.
05 -
Pour chocolate mixture over baked crust and spread evenly with an offset spatula, covering entire surface.
06 -
Return pan to oven for 5 minutes to begin setting chocolate. Remove and cool at room temperature for 10 minutes, then refrigerate for at least 1 hour until firm.
07 -
Once chocolate is firm, arrange mini marshmallows in tight rows covering the surface. For large marshmallows, halve and place cut-side down. If using marshmallow fluff, spread evenly over chocolate.
08 -
Use a kitchen torch held 4-6 inches from marshmallows and move in sweeping motion until golden brown with some charred spots. Avoid burning by not lingering in one spot.
09 -
If no torch, set oven broiler to high and place pan on top rack, not too close to heat source. Broil 1-3 minutes watching constantly to achieve golden, evenly toasted marshmallows.
10 -
Let toasted marshmallows cool at room temperature for 15 minutes, then refrigerate for 30 minutes to fully set for clean cutting.
11 -
Lift dessert from pan using parchment overhang onto cutting board. Use a large sharp knife warmed under hot water then dried to slice into 12-16 bars, cleaning knife between cuts for neat edges.
12 -
Optionally drizzle melted chocolate, sprinkle crushed graham crackers, and flaky sea salt on top before serving.