Warning : 
This contains milk, nuts, and other potential allergens. Do not give this to anyone that has any allergy to any ingredients. 
This is not safe for children to be making with out supervision. Boiling water and spinning blades are involved. 

Who doesn't like chocolate milkshakes? If you or someone you care for would benefit from more calorie intake This high calorie drink can tried. 
If you know somebody that can be described as any of the following : picky eater, neurodivergent, dementia, geriatric, restricted diet no solid food, gaining weight for athletic aspiration, then give it a go. 

Milkshake formula : 
The nutrition proportions are similar to baby formula. 
baby formula proportions per 100 calories is close to  : 10g carbohydrate 40 cal, 6g fat 54 cal, 3g protein 12 cal, 

Tools needed : 
Blender. I use magic bullet. 
French press. The reason that I use a glass and steel french press is that coffee made in plastic machines tastes bad. 
Kettle to boil water for coffee. 
Measure cups : 
.25 = 1/4
.33 = 1/3
.5 =1/2
1
1 tablespoon

Ingredients in the order to add to blender : 
.5 cup hot coffee. Made by 2 tablespoons coffee grounds and 2.5 cups boiling distilled water in french press. Folgers black silk. 0 calories
1 cup heavy cream. 720 calories
.33 cup Now Sports whey protein isolate. 120 calories
Blend 10 seconds. Pour out half.
1 cup chocolate ice cream Lactaid. 300 calories
.25 cup honey. Keep honey off walls of blender. 250 calories
pour out half
2 tablespoon peanut butter. 180 calories

Total calories in 20 ounces= 1570
Total calories in 1 ounce = 78.5

Makes 25 ounces
I have found it is best to make 4 or 5 of these at a time. 
20 ounce styrofoam cups are a normal size coffee cup. Cups, lids, straws, and four cup carrier can be bought from gas stations. 
Biodegradable 20 ounce cups should be used instead of styrofoam. Environment pollution is a problem. 

Clean everything up immediately after or things will dry and be stuck together. 

Alternative ingredients : 

If a person is allergic to nuts but not allergic to coconuts then peanut butter can be replaced with coconut oil. 
Standard process POSSIBLE Protein Powder

links : 

https://www.nowfoods.com/products/sports-nutrition/whey-protein-creamy-chocolate-powder