In a small saucepan, stir together the raisins, lemon zest and O’Driscolls Irish Whiskey. Cover and warm over medium heat until the mixture is hot, about 2 minutes. Once steaming, remove from the heat and set aside to soak (cover tightly) for a minimum 1 hour (or up to overnight).
Spread evenly into the prepared pan and bake for 45-55 minutes, until a toothpick cake tester inserted into the center comes out clean.