Melt 30g of the butter over low heat in a nonstick frying pan. Add the mushrooms, cover and cook on low heat for 10 minutes, or until they are just softened.
Steam the asparagus spears for 5–8 minutes, or until tender.
Meanwhile, beat the eggs with the cream in a mixing bowl and season to taste with salt and freshly ground white pepper. Melt the remaining butter in a heavy-based saucepan. Add the egg and cream mixture and stir gently over low heat until the eggs are just beginning to set. Remove from the heat and keep the eggs warm while toasting the bread. Cut the toast into triangles and arrange in a toast rack.
Spoon the scrambled eggs onto individual, warmed serving plates. Arrange the mushrooms and asparagus spears alongside the eggs. Sprinkle the eggs with chives and serve immediately with the triangles of toast and a dish of butter.