In a large bowl or stand mixer, cream the butter, Crisco, and brown sugar for 5 minutes, scraping the sides and bottom.
Add 2 eggs and vanilla. Beat well, scraping sides and bottom.
Mix flour, baking soda, and salt.
On low, add in the dry ingredients and mix until just until the combined.
Add the oats. Stir until incorporated but do not over mix.
Cover the bowl and chill the dough in the fridge for 1-3 hours (or overnight).
Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper or silicone baking mats.
Scoop the cookies into round balls and place on the prepared baking sheets, leaving 2 inches in between cookies.
Bake for 10-12 minutes, or until the cookies are lightly browned around the edges, but still soft in the middle. Be careful not to overbake.
Remove cookies from oven and let cool on the baking sheet for about 5 minutes. Transfer to a wire rack and cool completely.