Place an eight-cavity silicone popsicle mold on a small tray or cutting board so it can be transferred to the freezer without bending.
Add the vegan Greek yogurt, maple syrup, peanut or sunflower seed butter, vegan protein powder, vanilla and salt to a high-powered blender or food processor. Blend until completely smooth, stopping to scrape down the sides as needed. Continue blending until the filling looks glossy and uniform.
1/4 cup (80 grams) maple syrup, 1/3 cup (80 grams) natural peanut butter, 1/3 cup (35-40 grams) vegan vanilla plant-based protein powder, 1 tablespoon vanilla extract, 1/4 teaspoon salt, 2 cups (480 grams) thick vegan Greek-style coconut yogurt
Check the consistency. It should be thick and creamy but pourable, similar to thick pudding. If it is too thick to flow easily into the molds, blend in milk 1 teaspoon at a time. Avoid adding more than necessary.
1-3 teaspoons plant-based milk
Divide the filling evenly among the eight cavities, using approximately 74–75 grams per cavity. Tap the tray firmly against the counter several times to release air pockets, then insert and straighten the popsicle sticks.
Freeze for at least 7 hours or overnight. The bars should feel completely solid before you attempt to unmold them.
If using a silicone mold, gently remove the bars without warming it. If using a hard plastic mold, you’ll likely need to run warm water around the outside for a few seconds, just until the bars loosen enough to release. Place them on a parchment-lined tray and return them to the freezer for 15–20 minutes.