Preheat oven to 350°F. Melt the butter. Line a cookie sheet with parchment paper, and measure all ingredients. Allow the butter to cool for at least 15 minutes before beginning.
1/2 cup butter
In a medium sized bowl, add in flour, oats, cornstarch, cinnamon, nutmeg, allspice, cloves, ginger, baking soda, baking powder, and salt. Stir to combine and set aside.
1 1/4 cups all-purpose flour, 1 1/4 cups rolled oats, 1/2 tsp baking soda, 1/2 tsp baking powder, 1 1/4 tsp cinnamon, 3/4 tsp ginger, 1/2 tsp cloves, 1/8 tsp nutmeg, 1/8 tsp allspice, 1 tsp cornstarch
In a medium bowl, add in melted and cooled butter and brown sugar.
1/2 cup butter, 1/2 cup dark brown sugar
Add in the eggs, molasses, and vanilla. Continue whisking until smooth.
2 eggs, 3 tbsp molasses, 1 tbsp vanilla
Mix in the dry ingredients and using a spatula, gently fold until a batter forms. Do not over-mix!
Scoop the cookies onto a baking tray, about 1-1.5tbsp per cookie spaced 2-3 inches apart. These cookies don't spread much, so gently flatten the cookies into an oval-like shape before placing them in the oven.
Bake 6 at a time for 12-15 minutes or until the middle has set. Mine took 15 minutes exactly.
Store in an airtight container for up to 3 days or in the fridge for a week. You can also freeze the cookies and thaw in the microwave when wanted.