Preheat oven to 375 degrees F.
Process graham crackers in food processor or crush into coarse crumbs.
Add butter and peanut butter and blend.
Spread mixture on bottom of 9 x 13 baking dish to form crust.
Sprinkle with chocolate chips; drizzle with milk to cover chips.
Bake for 30 minutes or until top is bubbly. Cool completely.
Just before serving, sprinkle with marshmallows.
Broil 3 to 4 inches from heat until lightly browned.
Let stand a few minutes before cutting into 24 bars.