Today's equivalent of a cake of yeast
You can find fresh cake yeast in grocery stores, but it's much less common than active dry yeast granulates.
1 cake of fresh yeast is approximately the same as 1 envelope/packet of active dry yeast. 1 packet usually equals about 2¼ teaspoons, or ¼ ounce, or 7 grams of active dry yeast granules.