Preheat oven to 200°C fan. Toss pumpkin, capsicum, zucchini with oil and oregano. Roast on a tray 25 minutes until tender. Cool slightly.
Bechamel: melt butter, whisk in flour, cook 1 min. Slowly add milk whisking. Simmer 5 min until thick. Add nutmeg, salt, pepper.
Ricotta layer: mix ricotta, egg, sage and parmesan in a bowl. Salt and pepper.
In a deep 22x32cm baking dish, spread a thin layer of bechamel. Top with pasta sheets.
Layer: half the roasted veg, third of the bechamel, pasta. Half the ricotta mix, pasta. Remaining veg, third bechamel, pasta. Remaining ricotta, pasta. Final bechamel.
Top with parmesan and mozzarella.
Bake 35-40 minutes until top is deep golden and edges are bubbling. Rest 15 minutes before cutting.