Preheat oven to 350 F, line a 9x13 inch pan with foil and grease well.
To make the filling:
Melt the caramels, cream and peanut butter in a microwave safe bowl until creamy and smooth. Do this in short intervals (about 30 seconds) at med power, checking and stirring frequently to prevent burning.
14 ounce caramels
Set aside to cool slightly.
1/4 cup heavy cream, 1/2 cup creamy peanut butter
To make the brownie batter:
Melt chopped chocolate and butter in a large microwave safe bowl until smooth.
1 cup butter, 12 ounce chocolate
Whisk in sugar, eggs, and vanilla until incorporated (I recommend whisking the eggs in one at a time until well combined for each).
1 1/2 cup sugar, 5 eggs, 1 tablespoon vanilla extract
Stir in the flour and salt until just combined.
1 1/4 cup all-purpose flour, 1/2 teaspoon salt
Gently fold in the peanut butter cups.
8 ounce peanut butter cups
To assemble the brownies:
Spread about half the batter in the bottom of the prepared pan.
Spread the cooled caramel over the brownie batter in the pan, leaving about 1/2 inch of exposed brownie batter all the way around. (If the caramel mixture is too firm, heat briefly in the microwave to loosen it a bit)
Place the pan in the refrigerator for about 20 minutes or so to allow the caramel layer to set.
Spread the remaining brownie batter evenly over the top of the caramel layer.
Sprinkle the milk chocolate and peanut butter chips over the top of the brownie batter.
1/2 cup milk chocolate chips, 1/2 cup peanut butter chips
Bake for about 35 minutes, the top should look dry and set and the caramel may be bubbling around the edges.
Allow the brownies to cool completely before slicing, for easier slicing chill for 1-2 hours in the refrigerator. Cut the brownies into 24 large or 48 small bars (I usually opt for the smaller bars because I like to mix and match my treats)