Preheat oven to 350 degrees.
Line 24 muffin cups with paper or foil muffin liners.
In a large bowl beat together all the cupcake ingredients (cake mix, milk stout, vegetable oil and eggs) with a hand mixer on low speed. Scrap down the sides of the bowl with a spatula. Then beat the cupcake batter on high for 2 minutes.
Evenly divide the cupcake batter among the 24 muffin liners.
Bake the cupcakes for 18 - 22 minutes, or until a toothpick inserted into the center comes out clean.
While the cupcakes are cooling, add the softened butter, cream cheese, black raspberry jam and vanilla to a large bowl. Beat together with a hand mixer. Start on low speed and then beat on high for a couple of minutes until smooth.
Add the powdered sugar and salt. Again beat with the mixer on low speed to incorporate the sugar and then beat on high for 1 minute.
The frosting will be soft. I refrigerated my frosting for a couple of hours before frosting the cupcakes.