Add a pan to the hob over a medium heat and add some olive oil.
When heated up, add the onion and cook until soft. Normally about 8 -10 minutes.
Add the spinach and a little splash of water. Place the lid on the pan and cook for a further 8 – 10 minutes.
Add the mustard and flour and stir well.
Slowly add the milk stirring constantly. You should end up with a creamy sauce (greenish) with no clumps of flour.
Remove from the heat and add salt and pepper to season. Taste and adjust if necessary.
Add the leftover chicken (cut up or torn apart)
Add the sliced basil leaves.
Grate the cheddar cheese and add half to the pan.
Mix thoroughly so that everything is evenly spread.
To fill the cannelloni, you will need a piping bag or a freezer bag with the corner cut off.
Spoon the filling into the bag and fill each cannelloni tube up. Place the tubes into a dish large enough for them all. For 16 tubes a dish 10inx12in is perfect.
Time to turn the oven on to preheat to 350F/180C/Gas Mark 4
When you have finished filling the tubes, give the pan a quick wipe and then add the olive oil.
Add the garlic to the hot oil and cook until golden brown. Add the tomatoes (2 tins), the chilli flakes and about half a tomato tin of water.
Bring to a boil and then season tasting as you go to get the correct flavour.
When seasoning is perfect, pour the sauce over the cannelloni making sure it gets into every gap.
Add the remainder of the grated cheese over the top and place in the bottom of the oven for about 25-30 minutes until the dish is bubbling and golden.
Serve lovely and hot with garlic bread for a filling dish every time.