You can do anything you want with a smoothie! Don't worry about recipes.
Consider frozen stuff, like chopped kale or spinach, and frozen fruit. Just take a little out of the bag and put it in lukewarm water for a few minutes while you gather the other ingredients, and it will give you a cold shake. It's always on hand, it's cheaper in the winter, it's often more nutritious because it's frozen fresh-picked rather than being an out-of-season fruit shipped 2000 miles or more and being nutrient-deficient by the time you get it. I don't put the freshest and most delicious fruit in mine - I do find a smoothie is a good use for slightly soft or "ugly" fruit that are too good to throw out but too soft to enjoy in the usual way. My smoothies have my nutritional products (to cover all the vitamins, minerals and micronutrients), some kale, a half a banana (because it's always cheap and there's always one or 2 going soft on the counter), and whatever else I have on hand. Right now I'm doing a lot of watermelon, and I throw in the strawberry tops (leaves & core) that otherwise get thrown out. And I round it out with frozen fruit if I need it.
You can also keep flax seeds or flax meal on hand - those enhance any smoothie without changing the taste. Soft tofu works well too, to add more protein. Look for what's in your fridge that you have to get rid of - you'd be surprised what you can throw in there without it changing the taste.
Agave syrup or stevia can help sweeten things if you don't have a sweet fruit in there. Same with a splash of cranberry juice. You can use almond milk and also nut butters (almond, cashew, peanut). Also plain cocoa powder - very low in calories, no added junk like in many syrups).
Think about what you might choose as an ice cream flavor, and use that: chocolate & mint, maple syrup & walnut, etc. Skip the oreos and M&Ms, but you get the idea!
And 2 ingredients work fine - you don't need 5 or 12!