Preheat the oven to 400°F (200°C). In a large bowl, combine the bread mix with the rosemary, then make up the dough and knead following the package instructions. Allow the dough to rest for about 5 minutes.
Using a rolling pin, roll out the dough to approximately fit a shallow roasting pan that measures about 27 x 40 cm. Push the dough into the corners to make a neat fit. Cover lightly with a clean dish towel and set aside in a warm place while you prepare the topping.
Place the anchovies in a small bowl and cover with the milk. Allow to soak for 5 minutes, then drain and finely chop. (This soaking will remove the excess salt from the anchovies.)
Spread the tomato sauce all over the pizza crust, right up to the edges. Scatter the sliced mushrooms over the pizza, then flake over the tuna. Dot the tomato pieces, capers and chopped anchovies all over. Using a teaspoon, add little mounds of ricotta over the top, then drizzle evenly with the olive oil.
Bake for 25 minutes or until well risen with a golden crust around the edge. Transfer to a wire rack to cool slightly, then cut into six pieces. Scatter the basil over the slices and serve warm.
Variations: If your children do not like the strong flavours of anchovies and capers, replace them with diced red peppers, corn or cubed smoked ham.' You could add a handful of sunflower seeds, pumpkin seeds or sesame seeds to the dough for a nutty flavour and texture.
Each serving: 25 g protein, 9 g fat of which 3 g saturates, 43 g carbohydrate, 4 g fibre, 364 Calories