Peel squash, clear of seeds, cut into 2 cm wide pieces and mix with coarsely chopped onions. Bake on a sheet pan in the oven for 20 minutes at 250 °C, mince with tomatoes (without skin). Add vegetable oil, sugar and bay leaf. Stew for 30 minutes until the mass thickens. Season the spread with salt, vinegar and black pepper. Pass through a sieve and simmer under the lid for another 30 minutes. Take out the bay leaf and place the cooked spread in sterilized jars (f you want to preserve it for the winter). The squash spread is ready.