Cook spaghetti in boiling salted water for about 8 minutes, then drain. Drain artichoke hearts and cut in half. Clean and wash the peppers and spring onions. Cut the bell peppers into fine strips and the spring onions into rings.
For the sauce, peel the garlic and press it through the garlic press. Melt the fat. Sauté the garlic in it. Add flour and sauté. Deglaze with 250 ml milk and broth. Bring to the boil while stirring constantly.
Sprinkle in parmesan. Season to taste with salt and pepper. Whisk remaining milk and egg yolk and stir into the sauce (do not let it boil anymore!). Line pizza tray (28 cm Ø) with spaghetti.
Pour half the sauce over it. Add spring onions, peppers, olives, artichokes and dried tomatoes. Pour the rest of the sauce over it. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 40 minutes.
Serve garnished with fresh herbs.