I must say I am the self anointed Vitamix Queen, so I think I am qualified to answer. I first need to know what kind of blender you have? This is important to determining what all can go in there undetected by your picky eater. I'm going to assume you have a high power blender such as a vitamin.

1. Remember that Frozen Mango and Banana cover up the taste of almost everything.
2. Add almonds and or walnuts to all smoothies, but add at the beginning, to make sure it gets FULLY integrated into the smoothie.
3. If green is a problem, you can always add unsweetened coco powder and all it a chocolate milkshake to just about anything.
4. AVOCADO-add it to any and all smoothies
5. Whole fat yogurt, but add it at the end, the blending can denature the enzymes. You should really only add yogurt and the very last second and only blend for a second (literally as second).
6. Coconut milk is a great base, especially the chocolate kind. Personally I do not use the thick stuff out of a can.
7. My favorite if I want the kids to have high calorie and to down it fast? 1 Whole Avocado, Chocolate Coconut milk, one scoop BP, small scoop unswetened coconut powder, and a touch of Whole milk yogurt at the end. This one packs a lot of punch and tastes really good.

Where do you get digestive enzymes from? Any specific brand recommendations?

-Full-fat coconut milk, frozen bananas and strawberries (or whatever berries your DC prefers).

Coconut milk has healthy fats and far less sugar than milk or ice cream.

Just make her a milkshake, for the love of Pete. We still give my ds a milkshake several nights a week. I would recommend giving it to her after dinner so as not to interfere with her appetite.

It's possible that her tummy hurts when she eats due to a leaky gut. If you give her digestive enzymes in her smoothie, she'll absorb more nutrients and gain some much needed weight. Digestive enzymes will also help heal her gut. You can buy them in capsules and dump them right into the smoothie.

I don't make high-calorie smoothies but our typical recipe is a thick yogurt (my kids like Yoplait thick & creamy), milk, and whatever fresh or frozen fruit they choose (I keep bags of various frozen fruits in the freezer for smoothies). I sometimes add some Carnation Instant Breakfast powder.

To make this higher calorie, I would use whole milk yogurt (I love Greek yogurt but my kids find it to be a little "tangy" so maybe choose another whole milk yogurt if that's an issue), whole milk (or even a mixture of maybe 3/4 cup whole milk & 1/4 cup cream, to add more calories & fat) and any fruit your child likes.

Does your child like peanut butter? You could try a chocolate-peanut butter smoothie using whole milk, chocolate Instant Breakfast powder, and peanut butter.

Definitely start with whole milk yogurt. Thick Greek yogurt would be even better. Thin out with whole milk, then add powdered milk, protein powder, honey, flax seed, and/or molasses (good source of iron too). I've put olive oil and cream of wheat in my kid's, but he's younger and perhaps not as picky as some preschoolers might be. Chocolate syrup hides a multitude of taste sins.

You could modify regular smoothie recipes to include whole milk yogurt, protein powder, even avocado if she'll drink something green.

DC is 3 years and only 24 lbs! She eats everything but in very small quantities. I am looking for high calorie smoothie recipes.