Preheat oven to 325˚F.

Combine cake mix with eggs, oil (or applesauce), and water. Mix just until no lumps remain.

Spray 6-cup bundt pan with non-stick cooking spray. Spray generously, but not so much that there are pools of oil on the bottom.

Bake for 28-32 minutes, just until the cake is fully cooked and the top is firm (and a toothpick comes out clean).

Let cool for about 10 minutes. Then use a narrow silicone spatula to separate the cake from the pan, and turn the cake onto a plate.

Let the cake cool completely.

Make the icing by mixing the confectioners erythritol, lemon zest, and 2 tablespoons water to start. Mix well, and see if you need the other ½ tablespoon water (or more) to get the thickness you desire.

Drizzle icing on cool cake, and enjoy! Store refrigerated.