Closely adapted from King Arthur. The white chocolate is optional--leave out if you think you will especially enjoy the malty depth of the ale; if you have a super sweet tooth, then use it.
This recipe uses a mixer but it also uses some saucepans, plus it requires chilling time, so read through the entire recipe before starting.
Gently bring the ale to a simmer in a medium saucepan over medium low heat, stirring occasionally. Pay close attention and reduce the heat if it begins to foam up.
Keep simmering the ale, stirring often, for about 15 minutes, until it thickens and reduces to 3 tablespoons or 1 1/2 ounces. Set aside to cool.*
In a new medium saucepan set over low heat, heat the butter, molasses, 2 1/4 cups sugar, and salt. Stir often, until the butter melts and the sugar and salt dissolve, about 10 minutes. Remove from the heat.
Stir the spices and the amber ale reduction into the butter mixture. Set aside to cool for 10 minutes.
Whisk together the flour and baking soda in the bowl to a stand mixer (or a large bowl and use a hand mixer for the following). Turn the mixer to low and slowly pour in the liquid ingredients. Scrape the sides and bottom of the bowl.
Add the egg. Mix until well blended and a thick batter forms. Stir in the white chocolate chips if using.
Preheat the oven to 350°F. Line two baking sheets with parchment paper or silicone mats.
Whisk the 1/2 cup fine sugar with the Swedish pearl sugar in a shallow bowl. Place it beside the prepared cookie sheets.
Scoop the dough into 2-tablespoon sized balls. Roll the dough balls in the sugar to coat, then place on the prepared baking sheets, 2 inches of space between them (I baked 12 to a sheet).
Bake the cookies for 14 minutes, until the edges start to brown. Let them rest for 5 minutes on the cookie sheet, where they will continue to bake outside of the oven.
The cookies will be crispy and chewy, and will store well in airtight containers when cooled completely.
*If you feel compelled to taste the reduced ale, expect it to be quite strong and quite bitter. Don't worry!