Preparation
Step 1
Put the spinach in a sieve and pour over boiling water to wilt. Cool, transfer to a clean tea towel and squeeze out the excess water. Chop.
Step 2
Set a saucepan with the oil over a medium heat. Cook the onion for 5 minutes, stir in the garlic and cook for 1 minute. Add the pasta sauce, remove from the heat and cool slightly. Stir in the tuna and spinach.
Step 3
Preheat the oven to 180°C, gas mark 4. Dip the cannelloni into a bowl with warm water. Stuff with the sauce mixture. Spread the remaining sauce over the bottom of a medium baking dish and arrange the cannelloni on top.
Step 4
Melt the butter in a saucepan. Whisk in the flour until smooth then slowly pour in the milk, whisking until there are no lumps. Stir in the two cheeses. Spoon over the cannelloni, scatter with extra cheese then bake in the oven for 20 minutes. Garnish with basil.