In a mixing bowl, measure and add the flour, soda, salt, cinnamon and nutmeg. Whisk to combine and set off to the side.

In the bowl of your stand mixer, fitted with the paddle attachment, cream the butter on low to medium-low speed until pale in color. Add both the sugars and mix until combined

Add one egg at a time, mixing until just combine before adding the second egg along with the vanilla extract.

Gradually add in the flour mixture until combined and then mix in the oats.

Use a 2-tablespoon scoop to measure out 12 cookies per pan. Bake for 5 to 5-1/2 minutes before rotating the pans (back to front) and continue baking for an additional 5 to 5-1/2 minutes. Or until the edges are lightly golden brown.

Once the cookies have cooled on the pan for a couple of minutes, transfer them to a wire rack to cool completely.

In the bowl of your stand mixer fitted with the paddle attachment, cream the butter until fluffy and pale in color.

Switch over to the whisk attachment and gradually add in the sifted powdered sugar.

Once incorporated, add in the vanilla and milk. Increase the speed of your mixer until the buttercream is light and airy.

Measure a tablespoon on to 1/2 of the cookies and place the second half on top, lightly pressing to flatten the frosting.