• Preheat oven to 350°.
• In a stand mixer or with an electric hand mixer, cream together the butter, brown sugar and sugar until light in color and fluffy in texture.
• Scrape the sides of the bowl and add in the egg and canola oil. Mix until well combined.
• Add the flour, rolled oats, cornstarch, cinnamon, soda and salt. Mix until the dough forms.
• Portion the dough out -For small cookies, use 1 1/2 tbsp of dough for each cookie. For medium cookies use 3 tbsp of dough. For large cookies use 1/3 cup of dough.
• Roll the dough into a ball. Break the dough in half and then press the two halves back together leaving the jagged edge up. This will give your oatmeal cookie that classic texture. Arrange on a silicone or parchment paper lined cookie sheet.
• Bake at 350°. For small cookies, bake for 8-10 minutes. For medium cookies bake for 10-13 minutes. For large cookies bake for 12-15 minutes. The cookies will spread slightly and no longer look wet and glossy on top when they are ready to come out of the oven.

Icing

• While to cookies are baking, make the icing.
• Make the icing by combining the butter and shortening until smooth. Add in the powdered sugar, vanilla and 1 tbsp of milk. You can always add more milk, if needed. The icing should be quite thick.
• Transfer the icing to a zip top bag with the corner clipped or piping bag.
• When the cookies come out of the oven, allow them to cool on the pan for 3-5 minutes.
• After the cookies have cooled just slightly, zig zag the icing on top of the cookies. Allow the icing to melt and then use a spoon to push the icing to fill up all the dips in the texture on the top of the cookies.
• Allow the cookies to finish cooling on the pan.
• Enjoy!