Grease round microwavable dish, 8″ x 1-1/2″.
Microwave chocolate in 2-quart microwavable bowl on high (100%) until melted, 2 to 3-1/2 minutes.
Add shortening. Microwave until melted, 1-2 mintues.
Beat in sugar, vanilla and eggs until smooth.
Stir in flour, baking powder and salt. Spread in dish.
Microwave uncovered on high 2 minutes; rotate dish 1/4 turn.
Microwave until set but not dry, 1-1/2 to 2-1/2 minutes longer. (Parts of dough will appear very moist but will continue to cook while standing.)
Place mint patties on brownies in 3 rows.
Microwave on high until filling melts out around chocolate coating, 2 to 3-1/2 minutes.
Spread over brownies; cool.
Cut into wedges or bars.