In a medium bowl, whisk together all-purpose flour, salt, baking powder, baking soda, and cinnamon. Set bowl aside until ready to use.
Place room temperature Kerrygold unsalted butter in a large bowl and beat for about a minute with an electric hand mixer. Then, add dark brown and white sugars. Beat for about two minutes. Next, beat in Lyle's Golden syrup, vanilla extract, and a room-temperature egg.
Scrape down the sides of the bowl. Then, add the flour mixture, about ½ cup at a time, beating well after each addition. Add Irish steel-cut oats and use a silicone spatula, or wooden spoon to stir into the dough. Next, stir in toffee bits. Allow the dough to sit for ten minutes undisturbed in the bowl.
Put on a pair of vinyl gloves and line a quarter sheet pan with parchment paper. Then, portion the dough into balls using a one-ounce ice cream scoop and place the balls on the prepared pan.
Line a large freezer-proof container with a lid with parchment paper. Roll each ball of dough between your gloved hands and flatten slightly into a disk. Place the disks of dough into the prepared container. All of the dough disks will not fit in a single layer, so place another piece of parchment on top of the first layer. Continue placing the dough disks in a second layer on top of the parchment. Put the lid on the container and place it in the freezer overnight, or for at least eight hours, until the dough is frozen solid.
When you're ready to bake the cookies, preheat the oven to 350°F.
Line three half-sheet pans with silicone baking mats or parchment paper. Place eight dough disks on one of the prepared pans, two inches apart, and bake in the oven for 12-15 minutes, or until golden brown all over. Make sure to keep the dough frozen until ready to bake, and bake only one pan at a time.
Remove the pan from the oven and allow the cookies to cool for ten minutes on the pan. Once the first pan is out of the oven, bake the second pan, and so forth.
After ten minutes of cooling on the pan, transfer the Irish Steel-Cut Oatmeal Cookies to a wire cooling rack. Allow to cool completely, then store in an airtight container for up to a week.
Yield: 22 cookies