Preheat your grill or a grill pan over medium-high heat. Lightly brush the cut side of the peach halves with a tiny bit of oil or butter. Place them cut-side down on the grill and cook for 3 to 5 minutes until distinct grill marks appear and the fruit softens. Remove from heat and let them cool for a few minutes.

Once the peaches are cool enough to handle, you can choose to peel them or leave the skins on for extra fiber. Roughly chop the grilled peaches into smaller chunks so they blend more easily.

In a high-speed blender, add the almond milk first to prevent the powder from sticking to the bottom. Add the grilled peach chunks, vanilla protein powder, Greek yogurt, cinnamon, sweetener if using, and the ice cubes.

Secure the lid on your blender and start on a low speed, gradually increasing to high. Blend for about 45 to 60 seconds until the mixture is completely smooth and creamy with no ice chunks remaining.

Give the smoothie a quick taste. If you prefer it thinner, add a splash more milk. If you want it sweeter, add a touch more honey. Pour into a tall glass and enjoy immediately.