In a large bowl, mix together the cake and pudding mixes, sour cream, oil, beaten eggs and water. Stir in the poppy seeds and lemon zest and pour batter into a bundt pan sprayed with nonstick cooking spray.
Bake for 45-50 minutes, or until top is springy to the touch and a wooden toothpick inserted comes out clean. Cool cake thoroughly in pan for about 90 minutes before inverting onto a plate. If desired, dust the cake with powdered sugar or top with lemon glaze.
Whisk to combine. If it's too runny, add more powdered sugar until it's the consistency you prefer.
Notes
When making the lemon glaze, add more powdered sugar if it’s too thin, or more milk if the glaze is too thick.