1. Preheat the oven to 350 degrees F. Arrange 6 individual tartlet pans with removable bottoms on a baking sheet. Spray tartlet pans with nonstick cooking spray. Blend the Maria crackers and brown sugar in a processor until coarse crumbs form. Add 8 Tbs. butter and process until the crumbs come together. Press the crumbs into the prepared tartlet pans. Bake until tartlet shells are golden brown, about 10 minutes. Cool completely.
2. In a small saucepan add chocolate chips and half-and-half. Melt chocolate chips at low heat and stir occasionally. Remove from heat and let cool for about 5 minutes. Smear chocolate mixture on tartlets and refrigerate until assembling.
3. Add 3 marshmallows to center of each tartlet. Use a torch to roast marshmallows till charred in spots.