Hi,
I have just looked up the recipe and it only says baked beans and not the make, and I agree, not the size. The calories are estimated at 260cals per serving. 2 Portobello mushrooms – estimate 40 cals, mozzarella – a handful (?) say 20 grams is 60 cals so that leaves 160 cals for the baked beans. I just looked up the Sainsbury’s website and for a 415g can of Heinz baked beans, half of that is 164 cals – so it is likely this recipe is for that size of can.
As to which brand you use and the sugar content, so long as you count it within your carb and or calorie allowance, then your own personal circumstances will dictate which you choose – the sugar may cause a spike for diabetics, but be ok for others.
Hope that helps.