The below recipe is what I made for one, and I had a little left over. I doubt it could have served two though.
Spinach and ricotta zucchini cannelloni:
1 small onion
2 cloves of garlic
1 tin of chopped tomatoes (400 grams)
1 tsp butter
1 tsp plain flour
150 ml milk
150 grams frozen, chopped spinach, defrosted
100 grams ricotta cheese
Salt and pepper
First, make your favourite tomato sauce (or crack open the jar, if your favourite comes in one of those). I sautéed a finely chopped onion and a couple of cloves of garlic, poured over a tin of chopped tomatoes, seasoned with salt and pepper, added some fresh basil and left it to simmer while I got on with the rest of it.
Next, prepare a bechamel sauce. Seeing as I was only making enough for myself, I used just a teaspoonful of butter, the same amount of plain flour, and 150 millilitres of milk. Regardless of the quantities you are using, make a roux by melting the butter and stirring in the flour, then add the milk gradually and bring to a boil, stirring constantly until the sauce thickens. Season with salt, pepper and nutmeg.
T0 make the cannelloni, wash the zucchini and trim the ends off. Now cut it into thin slices lengthwise. I found this tricky and actually mauled an entire zucchini trying to make it work (thankfully I had bought two). I tried using a carrot peeler, but it wasn't wide enough. I ended up using my mandoline, which made slices that were far too thick, and then carefully slicing those in half.
In a bowl, mix spinach and ricotta, and season with salt, pepper and nutmeg. Now lay out three or four zucchini slices next to each other on a cutting board, overlapping slightly by about half a centimetre. Place a couple of spoonfuls of the spinach and ricotta filling in a line across all the zucchini slices, close to the end nearest you, and roll up the zucchni slices into a little tube around the filling.
Spread out some of the tomato sauce over the bottom of an oven proof dish. Arrange the zucchini tubes next to each other on top of the tomato sauce, top with the remaining tomato sauce, the bechamel sauce, and perhaps a sprinkling of parmesan cheese. Bake at 200 degrees for about 30 minutes, or until the bechamel sauce is golden and the zucchini tubes are soft.
I had this as is, but had I been less impatient, or maybe serving it to company, a simple salad with rocket leaves and roasted red peppers, and maybe a nice glass of red wine, would have suited this dish well.