The Happy Corner is located in the little row of restaurants inside the Brupark, where Mini-Europe, the Atomium, and a water park are located. The food is a mix of French and Belgium specialties, and they have both indoor and outdoor seating.
My wife had the 1/2 Poulet Roti, which was half of a chicken, fries and a salad. There was a lot of food and it was very good for the price. I had the Carbonnades a la Flamande, a Flemish dish similar to a roast with a mustard based brown gravy. The meat was very tender and fell apart when cut with a fork.
Both dishes were an excellent value at under 10 euro each. This was the cheapest dinner that we had in all of Brussels, which surprised us since it was in the middle of a tourist area.