I found this on another forum:
"Birra Moretti
Brewery: Heineken Italia in Milano, Italy
Style: Pale Lager
OG: 1045
ABV: 4.6%
Grainbill: 70% Pale, 30% Flaked Maize
Hops: Hallertau
IBU: 21
Colour: clear straw
Yeast: probably Heineken A-yeast, Dr Elion's 1886 pure yeast culture"
You could swap out some of the pale malt for light DME, maybe around 50%. If I was you and making a partial mash recipe, I'd start with trying to create it on Brewer's Friend and try to get somewhere near to the numbers above. For reference, 2KG of grain is equal to 1.2kg of DME, and that should be somewhere near to 50% of the grain bill.
Flaked maize shouldn't be used as more than around 30% of the grain bill, so take that into account when you are making your recipe. If you need any help or want anyone to point you in the right direction just ask, I'm sure someone will pitch in to help.
I haven't checked the numbers but the grain bill for around 20L should look something like:
1.2kg light DME
1.4kg pale malt
0.6kg flaked maize
If I was aiming for 21 IBUs I'd try something around 30g of Hallertau around 60 mins then maybe 20g-30g at 15 mins.
It's not exactly the same as the moretti recipe but won't be a million miles away. But don't take this as a finished recipe it's just a starting point to get you in the ballpark. Inputting those numbers into Brewers friend should tell you how close it is.
Good luck!