Preheat the waffle maker completely. A properly heated iron helps the outside set quickly and gives the waffles better browning.
Whisk the egg in a medium bowl until the yolk and white are fully combined.
Add the heavy cream, water, vanilla, and sweetener and whisk until the mixture looks even.
Add the Carbquik baking mix and gently stir until you no longer see dry patches. Do not keep mixing once the batter comes together.
Pour in the oil and stir just until incorporated. The batter should be thick enough to spoon easily but still spread when the waffle maker closes.
Lightly grease the hot waffle plates if your waffle maker tends to stick.
Add enough batter to cover most of the center of the plate without filling it to the edges. The exact amount depends on the size and shape of your waffle maker.
Close the lid and cook until the waffle is golden and the steam coming from the iron has noticeably reduced. Start checking around 4–5 minutes, but use your waffle maker's normal cooking behavior as the final guide.
Open the waffle maker carefully and lift the waffle out with a silicone or wooden utensil. Avoid using metal utensils on nonstick plates.
Let the waffle sit on a cooling rack for a minute or two if you want the exterior to stay crisp instead of trapping steam underneath.