My daughter (age 4) likes tuna melts (slice of bread, canned tuna, grated cheddar... into the toaster oven or under broiler), peanut butter and banana pinwheels (tortilla shell spread with peanut butter and some banana slices, roll up and slice into pieces), and cheddar quesadillas (two tortillas with grated cheddar between, cook in fry pan with a bit of oil to lightly brown on both sides and melt cheese).
These would be just fine for a 1.5 year old too.... provided there's no allergies!