Here are some of the major factors: 1. Ratio of ingredients: The amount of flour, sugar, and fat in a cookie recipe can affect the texture of the cookies. Generally, cookies with a higher ratio of sugar and fat will be softer and chewier, while cookies with a higher ratio of flour will be crisper. The moisture content of the dough can also affect the texture of the cookies. Cookies made with moist ingredients, such as brown sugar or syrup, will be softer and chewier, while cookies made with drier ingredients, such as granulated sugar, will be crisp. That's why I use a combination of brown sugar, white sugar, and yogurt or applesauce to give these cookies the perfect soft and chewy texture. 2. Baking temperature and time: Baking cookies at a lower temperature for a longer time can result in softer, chewier cookies, while baking at a higher temperature for a shorter time can result in crisper cookies. The exact baking time and temperature will depend on the recipe and the desired texture. 3. Type of fat: The type of fat used in a cookie recipe can also affect the texture of the cookies. As I mentioned earlier, butter has a lower melting point than shortening, which can cause cookies to spread more and result in thinner, crisper cookies. Shortening has a higher melting point than butter, which can help cookies hold their shape and result in thicker, chewier cookies. This is a recipe for chewy chocolate chip cookies, which is why it uses shortening instead of butter. 4. Resting time: Resting time can also affect the texture of cookies. Allowing the cookie dough to rest in the refrigerator for a few hours or overnight can help the flavors develop and create a chewier texture, which is why it's important to chill the dough in the fridge at least two hours for this recipe.