Heat oven to 375ºF and place rack in center. Line a baking sheet with parchment paper.
In a food processor, process 2 cups oats and the raisins until finely ground. Transfer to a medium bowl; stir in remaining 1 cup oats, the flour, baking powder, salt, cinnamon, ginger and cloves; set aside.
In a mixer bowl, beat together granulated sugar, brown sugar, butter and shortening on medium speed, scraping down sides of bowl occasionally, until light and fluffy, about 2 minutes. Add egg, then extract; beat until combined. Stir in oats mixture until combined.
Roll dough into 1 ½-inch balls (2 tablespoons dough each). Place, 2 inches apart, on prepared sheet and lightly press to flatten. Bake until light golden brown around edges, 14 to 16 minutes. Transfer sheet to a wire rack and let cool slightly. Transfer cookies to rack and let cook completely.
For glaze, in a small mixer bowl, combine confectioners' sugar and meringue powder. With mixer on low speed, beat in 2 tablespoons water until mixture is the consistency of a medium-thick icing. Beat 3 minutes, adding water (if needed), 1 teaspoon at a time, to make a spreadable icing. Brush on cookies and let stand until set, about 30 minutes. (Store in an airtight container at room temperature, in single layers separated by waxed paper, up to 3 days.)
Use a dry pastry brush dipped in the icing to BRUSH it on! No drizzling, no spreading with a spatula or a knife. Those don't work! Brushing is the key.