Preheat oven to 425°F.
Place peaches skin-side down in a small pie plate or small baking dish. Sprinkle with water.
Stir together stevia and vanilla in a small bowl, until completely combined. Spoon the vanilla-stevia mixture into the cavity of each peach.
Cover the pan tightly with foil and bake for 20 minutes.
Uncover the pan and bake until the peaches are tender and the juices are syrupy, about 15 minutes more. (Add more water if the juices begin to scorch.)
Brush the peaches with the syrup from the bottom of the dish. Serve warm or at room temperature.
4 peaches, cut in half and pitted
1/4 cup water
2 teaspoons stevia
1/2 teaspoon vanilla extract