In a large bowl, use an electric mixer to cream together butter and sugars. Beat in the egg and vanilla extract. Slowly add the salt, baking soda, baking powder, flour and oats. Fold in the jelly beans.
Drop dough in rounded tablespoons on parchment or silicone-lined baking sheets. Bake for 7-9 minutes, or just until lightly golden brown. Cool on the baking sheet for a few minutes, and then transfer to wire racks to cool completely.
Notes
Any small jelly beans will work in this recipe. I used Starburst jelly beans (our favorite), but Jelly Belly or other brands are also great. If you'd like to use large jelly beans, I recommend cutting them in half before adding them to the dough.
To keep the cookies chewy and moist, remove the cookies from the oven when they’re just slightly browned (but still look a bit soft in the middle). They will firm up as they cool, but they will remain soft and chewy. If you want a crispy jelly bean cookie, bake these longer than the recommended 7-9 minutes. Finally, it’s important that you don’t over-mix the dough once you add the dry ingredients (which can result in tough, dry cookies).
I like how the quick oats blend into the cookies. If you prefer chewier, heartier oats in your cookies, you can use old-fashioned rolled oats instead. I do not recommend using steel cut oats.
Make sure that you line the baking sheets with parchment or silicone mats. This prevents the jelly beans from sticking as they bake.