Place the sliced peaches into the blender with the seeds scraped from the vanilla bean and the chili powder.
Add the ice cubes to the blender.
Blend everything on high speed until the mixture is smooth, frosty, and evenly blended, about 30-60 seconds. You should see a vibrant, slushy texture.
Pause the blender and taste the slushie. Adjust the chili powder if you want more heat, then give it a quick pulse to incorporate.
Pour the slushie into chilled glasses, allowing the icy mix to fill each glass smoothly.
Serve immediately with a straw or a garnish of fresh peach slices if desired, enjoying the refreshing balance of sweet, spicy, and aromatic flavors.