Wash the chervil and shake well dry. Put some stems aside for garnishing, put the rest of the chervil in a tall mixing bowl. Cut the avocado in half, stone it and remove the flesh from the skin.
Peel the garlic and press it in. Add lemon juice and puree everything with a hand blender. Briefly blend in the cream cheese. Season to taste with salt and pepper.
Drizzle baguette slices with oil. Wash the tomatoes and cut into thin slices. Spread on the baguette and season with salt and pepper. Use 2 tablespoons to cut the chervil-avocado mousse into cams and arrange them on the tomatoes.
Garnish with remaining chervil.
Drink tip: white wine, e.g. a Sauvignon blanc.