Baking – use tartaric acid in making Snickerdoodles

If they're tangier than you'd like that would be due to the acidity of the cream of tartar. While most recipes for Snickerdoodles do in fact us cream of tartar and baking soda for a homemade form of baking powder (most likely due to the fact that snickerdoodles are fairly "old"-style cookie), a few I looked at are using baking powder and no cream of tartar.

Here are a few things to know and a suggestion:

Acidic doughs do not spread easily and do not brown easily. Using the combination of cream of tartar in the 2:1 ratio w/ baking soda for leavening not only causes them to puff but with the higher acidic ratio it is also likely to help in keeping them more "cakey" and prevent them from browning as much.

You could try cutting back the cream of tartar slightly and seeing if that helps (possible drawback could be the soda making a more pronounced bitter soapy taste if there isn't enough acidity).

Or

Replace the cream of tartar and baking soda with baking powder. Baking powder by volume isn't as powerful as baking soda because of the fact it contains soda, two dry acids, and cornstarch. 1 teaspoon of baking powder will leaven 1 cup of flour (vs. 1/4 teaspoon of baking soda to leaven a cup of flour). If your recipe calls for 2 cups of flour then use 2 teaspoons of baking powder and cut out the cream of tartar and baking soda.

If you take the pecans out of pecan sandies, what you have left I believe is basically a short bread cookie, although those are traditionally presented in wedges.

Starting by searching for shortbread cookie recipe will give you a much better starting point.

These recipes tend to have a basis as simple as you list, although some embellish by dipping in chocolate and so on. Others substitute cornstarch for some of the flour, to help promote the frangible, delicate texture (cornstarch has no gluten precursors like flour, so it doesn't bring risk of creating a tough or rubbery cookie).

The recipes you are reading which contain baking powder probably (without reading the recipe, its difficult to say for sure) use it to... well... literally create a small amount of leavening, or airiness in the cookie. This will contribute to its crumbly texture, especially if some toughness from overworking the flour is present. As you have noted, it is not necessary in this type of recipe.

Side note: cream of tartar is an acid, not a leavening agent.