Preheat your oven to 350 degrees Fahrenheit and line 2 baking sheets with parchment paper and set aside.
In the bowl of an electric stand mixer (attached with a paddle), beat together the butter and both sugars until fluffy and light, about 2 minutes.
Add the egg, vanilla, and sea salt and beat on medium speed, mixing until combined well.
Remove from mixer and fold in flour, baking soda, and rolled oats using a rubber spatula. Once fully combined, gently fold in mini chocolate chips.
Scoop 1 Tbsp of cookie dough (or use a cookie dough scoop) and roll it into a nice ball, placing it onto the lined cookie sheet. Repeat until all dough is used. NOTE: Ensure that you leave at least 1-inch of space in between each cookie dough.
Bake them for 11-12 minutes, until edges and bottoms are golden brown. NOTE: At first, cookies will appear to be undone, however, they will harden and form better once fully cooled.
Once removed from the oven, allow them to cool for 10-15 minutes, before transferring them to a cooling rack to cool completely (about 30 minutes).
To assemble cookies---pipe 2-3 Tbsps of Wilton’s naturally flavored Warm Vanilla icing on one side of one cookie and place the other cookie atop. Next, sprinkle their Naturally Flavored Chocolate Jimmies and/or Naturally Flavored Vanilla Jimmies around the edges of the frosting in the middle or to make things easier: place sprinkles in a bowl and lightly roll the edges of the cookies in them! Repeat until all cookies are assembled.
Grab a nice glass of milk or non-dairy milk and enjoy! Bon Appetite!