McDonald, making his 17th straight start, stopped 33 shots and was perhaps the only bright spot for New York, which looked thoroughly disinterested most of the night in losing for the fifth time in six games.
Still, goals by Mike Sillinger and Bill Guerin left the Islanders one shot away from better things until Jeremy Williams fired home Blake's cross-ice pass 8:21 into the third to for the final margin.
Williams, called up from the American Hockey League on Sunday, also had an assist and helped form a solid unit with Blake and Dominic Moore.
The Maple Leafs headed into the third period before a crowd of 19,309 doing something they haven't done much of lately - protecting a lead.
Blake, who now has six points in his last three games, put the Leafs up for the third time with 1:39 left in the second. He took a brilliant thread pass from Williams, cut in off the right wing and fired a shot past McDonald's stick side for a 3-2 edge.
The Leafs' first two leads didn't last very long.
Sillinger tipped in a previously deflected point shot past Toskala for first of season at 16:07, just over 3 minutes after White fired home Anton Stralman's feed from the point on a power play at 12:56.
In the first, Kulemin opened the scoring 4 minutes in when he came off the bench on a line change, skated into the slot and slipped Alexei Ponikarovsky's pass by McDonald.
Kulemin's goal gave the Maple Leafs an 8-0 edge in shots, but the Islanders answered just 12 seconds later as Guerin tipped Freddy Meyer's dribbling point shot past a stunned Toskala.
While McDonald needed to make save after save to keep the Islanders in it, Toskala found himself with very little to do. He did come up with a big save midway through second period, when Tim Jackman stole the puck from White and broke in alone, only to be turned away.
Toskala also made a nice stop on Sillinger early in the third.
