Preheat oven to 350 degrees
Line square glass baking dish with parchment & give a light spritz with cooking spray
In large bowl combine flour, cocoa, baking soda & salt - whisk to combine
In a smaller bowl combine chocolate chips & butter - microwave in 30 second intervals until melted - allow to cool slightly
Add in sugar to melted butter & chocolate- stir
Add eggs, Irish Cream & vanilla. - Stir well until combined
Pour into dry mixture & fold until completely combined
Transfer to prepared dish
Bake for 20-30 minutes- might not appear done in the middle - that's okay, they will settle as they cool- that's what keeps it fudgy.
Remove from oven & immediately sprinkle top with Andes mint pieces allowing them to melt partially into the hot brownies.
Cool completely before cutting.