Boskoop is a great choice for apple pie because it has a well-balanced flavor that combines sweetness with a slight tartness. They have firm, dense flesh that holds up well during cooking so that the pie retains its structure and doesn't get mushy and doesn't release too much liquid that would ruin the dough. Alternatives to Boskoop are Granny Smith, Honeycrisp, Braeburn, Jonagold, Cortland, Empire and Northern Spy.
We recommend dark maple syrup because the rich caramel and notes of melted butter work well in baked goods and add to the flavor and do not get overwhelmed.