I've converted the linked recipe to grams because it's the most accurate and I've quadrupled the original amounts:
Cookies:
625 grams ap flour
9 1/3 grams baking soda (2 tsp)
12 grams salt (2 tsp)
326 grams buttermilk (1 1/3 cup)
8.5 grams vanilla extract (2 tsp)
300 grams butter
400 grams sugar
224 grams whole eggs (4 each)
Icing:
720 grams powdered sugar
85 1/3 grams corn syrup (1/4 cup)
40.5 grams lemon juice (1/8 cup)
4 grams vanilla extract (1 tsp)
86 grams cocoa
Now that it's been converted to weight, it's easy to scale up or down.
The original amounts have been quadrupled, so if you need a much larger batch, it's a cinch to double it.
Better now? Also, perhaps you should brush up on your conversion skills. Any self respecting PC masters that skill early on.
FUN FACT: There are a lot of ingredient conversion tools on the web! I even have an ingredient conversion app on my phone!
Here's a link to one of them:
https://www.thecalculatorsite.com/cooking/cooking-calculator.php