• Preheat the oven to 350°F. Line baking sheets with parchment paper.
• In a medium bowl, whisk together the flour, oats, ginger, cinnamon, cloves, nutmeg, allspice, baking powder, baking soda, and salt.
• In a large bowl, beat the butter and brown sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the molasses and vanilla.
• Gradually add the dry ingredients to the wet ingredients. Mix until just combined, being careful not to overmix.
• Scoop out 1 ½-tablespoon portions of dough and place them onto the prepared baking sheets, leaving space between each cookie. Gently flatten each cookie with your fingers or the bottom of a glass until they are about ¼ to ⅓ inch thick.
• Bake for 9 to 11 minutes, or until the edges are set and the centers still look slightly underdone. The cookies will continue to set as they cool.
• Let the cookies cool on the baking sheet for a few minutes, then transfer them to a wire rack to cool completely.

Icing

• To make the icing, whisk together the confectioners' sugar, 2 tablespoons of milk, vanilla, molasses, ginger, cinnamon, and cloves. Add more milk, a little at a time, until the icing is thick but pourable.
• Drizzle the icing over the cooled cookies, or dunk the tops into the icing. Let the icing set before serving.