Two. The answer is two.
His first came during the 2014 playoffs, shortly after the Philadelphia Flyers first traded for him and signed him to a contract that might have been just a little (okay, a lot) too generous. His second came during Game 4 of the first round of the 2016 playoffs.
The Flyers, facing elimination via first round sweep by the Washington Capitals, absolutely needed to have this game. And so far, they've looked calm, composed, and collected - and then MacDonald scored an insurance goal early in the second period to put Philadelphia up 2-0.