Add the raisins to a bowl, set them aside, and let them soak in water for at least 10 minutes to soften them.
Add the flax meal and water to a small bowl, stir, and let rest for 10 minutes, stirring occasionally to combine the two. This creates flax "eggs."
Add the rest of the wet ingredients to your standing mixer bowl along with the prepared flax eggs.
Beat this with the paddle attachment over medium-high speed for 3 minutes to make the mixture light and fluffy.
Add all of the dry ingredients, EXCEPT for the old fashioned oats and chocolate chips, to another mixing bowl and whisk to combine. Dump this into the standing mixer and beat over low speed until mostly combined. Do NOT overmix, or you will create tough cookies.
Drain the raisins, pat dry with a paper towel, and add them to the standing mixer along with the oats. If you are also adding chocolate chips, add them now. Mix on low speed just until combined. Again, do NOT overmix.
Wrap the dough in plastic wrap and place it in the refrigerator to rest for at least 1 hour.
Preheat the oven to 350 degrees Fahrenheit.
Line a large sheet pan with parchment paper. Portion 2 tbsp balls of dough per cookie and place them 2 inches apart.
Bake the cookies on the middle oven rack for 11-13 minutes. Bake them for 11 minutes for softer cookies and 13 minutes for soft-ish cookies with a bit more crunch on the outside. You can bake two sheet pans at a time if you have a large oven. If you bake two sheet pans at a time, rotate the pans halfway through baking to ensure the cookies bake evenly. Otherwise, repeat the last two steps until you've finished baking all the dough.
Allow the cookies to cool completely before removing them from the pan. *The cookies may look underbaked when you first pull them out of the oven, but as they rest, they will finish baking.