Add the milk to the blender first to help the blades blend easily.

Place frozen strawberries and frozen banana into the blender.

Add the peanut butter and Greek yogurt.

Add spinach if using for extra nutrients.

Drizzle in honey or maple syrup if additional sweetness is desired.

Blend everything on high speed until smooth and creamy.

Pause the blender and scrape down the sides if necessary.

Blend again briefly until the smoothie becomes thick and silky.

Pour the smoothie into a tall glass.

Serve immediately while cold and fresh.