Melt the butter and chocolate in a pan over low heat.
Using a mixer, beat the eggs and sugar until pale yellow and fluffy. Lower speed and pour in the melted chocolate and vanilla. Mix in the flour and 1/4 teaspoon salt. Fold in the peanut butter cups. Scrape into a buttered 9-by-13-inch baking dish. Bake until the tip of a knife comes out clean, about 35 minutes.
This has been stored as my go to recipe and will be making it to give to friends, take to picnics, etc. It should be noted that I like my brownies on the sweet side, so this was perfect for me (and my friends who tried it). Modifications I made: I halved the recipe and baked in 9-in. pan; used 2oz. semi-sweet & 2oz. UNsweetened chocolate; baked it at 350 degrees, NOT 400! Result: a super dense, chewy brownie w/ a nice crinkly crust on top. YUMMMM!
Eat Well. Lose Weight. Live Healthy. Delicious and healthy recipes customized for you!