Follow the steps in order for the best result.
In a small saucepan, combine the plump raisins with one cup of water. Bring this mixture to a rolling boil over medium-high heat, then reduce heat slightly and let it simmer gently for three minutes.
Once simmered, remove the saucepan from the heat and set it aside to cool completely. It's crucial not to drain the liquid, as it will be incorporated into the cookie dough.
In a large mixing bowl, using an electric mixer, cream together your chosen shortening or softened butter with the granulated sugar until the mixture is light, fluffy, and pale in color.
Gradually incorporate the lightly beaten eggs into the creamed mixture, mixing well after each addition. Stir in the pure vanilla extract until just combined.
In a separate medium bowl, whisk together the all-purpose flour, baking powder, baking soda, fine sea salt, ground cinnamon, and ground nutmeg. Gradually add this dry ingredient mixture to the wet creamed mixture, mixing on low speed until just incorporated.
Continue to blend until the dough is thoroughly combined and no streaks of flour remain, being careful not to overmix.
Gently fold in the finely chopped walnuts and the cooled raisin mixture, including all the water it was boiled in. Mix until evenly distributed throughout the dough.
Prepare your baking sheets by lightly greasing them or lining them with parchment paper. Drop spoonfuls of the cookie dough, about 1 ½ to 2 tablespoons each, onto the prepared sheets, leaving ample space between each cookie for spreading.
Preheat your oven to 350°F (175°C). Bake the cookies for 12 to 14 minutes, or until the edges are lightly golden brown and the centers are set. Transfer to a wire rack to cool completely.