Yummy Marshmallow Brownies

I really wish I could remember where I found this recipe.  It is a keeper and makes a lot so great for potlucks or church gatherings and I will warn you, very addicting!  I will post the lemon bars another time, they also are amazing and addicting!  Happy Eating :) 
                       Yummy Marshmallow Brownies
1c. butter
2c. sugar
1/3 c. unsweetened cocoa
4 eggs
1 1/2 c. flour
1 tsp. salt
2 tsp. vanilla
**Soften butter, and blend in sugar and cocoa.  Beat together and add the eggs, one at a time.  Add flour, salt and vanilla.  Spread on large greased cookie sheet (10x15x1inch), I use my jelly roll pan.  Bake 25 min. at 350F.  Remove from oven and cover entire top with 1 pkg. minature marshmallows.  Return to oven for 3 min., until soft and puffy.  Cool and frost with chocolate frosting.
Chocolate Frosting:  
1 stick butter (1/2c), softened
1/4c. milk (I sometimes use whipping cream or evaporated milk, it's richer, but really good!)
1  1/2 tsp. vanilla
1/4c. unsweetened cocoa
2 to 3 c. powdered sugar
**Mix all ingredients with a hand mixer until smooth.  Add more powder sugar or milk until you reach frosting consistency.