A classic side dish found in “Varme Småretter” (Small Hot Dishes) in the “Ingrids Beste” (Ingrid’s Best) series publishd by Gyldendal i 1991
If you think it’s a lot of work to first cook the vegetables and then gratinate them afterwards, you can use deep-frozen vegetables as a starting point.
Deep frozen broccoli or a blend of summer vegetables are excellent. Put the vegetables deep frozen in the mould and pour the sauce over them. Calculate 4-5 minutes longer in the oven for the frozen ones.