Crack the eggs into a bowl and beat until the yolks and whites are thoroughly combined. Mix in the cream or milk, salt and pepper.
Add oil or butter to a large, non-stick skillet set over medium heat. Add the eggs. As the egg begins to set on the bottom, gently move a heatproof spatula across the bottom and sides of the skillet to form large, soft curds. Continue cooking until the eggs are cooked, but still moist, with no visible liquid egg remaining.
Divide and arrange the tomato slices on 4 plates. Mound the eggs on the tomatoes. Set 2 slices of Brie on top of each mound; sprinkle with green onion and serve.