Pre heat oven to 350. Line 13X9 pan with parchment paper.
If using mix for cookies follow directions for dough, if using refrigerated dough or home made dough
Press dough into bottom of prepared pan.
Bake for 8 minutes
In microwave safe bowl combine sweetened condensed milk and chocolate chips.
Heat milk and chips until chips melt, stir smooth.
using a spoon drop spoonfuls of the chocolate mixture over the cookie base.
Return to oven and bake another 20 minutes. Or until set.