Mols, in his first match for five months after injury, headed Rovers into a 51st-minute lead at Leyland.
Nuttall (pictured) sealed the victory when he touched in his 21st goal of the season from close range in the 76th minute.
Blackburn host second-placed Aston Villa at Ewood Park next Monday and will win the title if they avoid defeat.
Rovers have two matches remaining and lead Villa, who have a match in hand, by seven points. Newcastle stay 11th in the table.
Blackburn: 16 Apr v Aston Villa (H) PL2
Newcastle: 12 Apr v Porto (H) Int Cup