Cut the arugula very finely. Cut the dried tomatoes very finely into cubes. Finely grate the Parmesan cheese. Beat the soft butter with a mixer until creamy.
Fold in arugula, tomatoes and Parmesan and season with pepper. Cut the baguette into slices and spread with the seasoned butter. Bake in a hot oven until crispy.
Cut the matie fillets into diagonal slices and place on the bread while it is still warm. Garnish with a little dried tomato and rocket.