In a small saucepan, combine 1 cup of water, 15 ounces of raisins, and 1 tablespoon of lemon juice. Bring to a boil, then reduce to a simmer. Let it cook for about 10 minutes or until the raisins are plump and soft. Remove from heat and let cool.
In a large mixing bowl, cream together 2 cups of granulated sugar and 1 cup of softened margarine until light and fluffy.
Add 2 large eggs and 2 teaspoons of vanilla extract to the mixture. Beat until well combined.
In a separate bowl, whisk together 6 cups of all-purpose flour, 4 teaspoons of baking powder, 2 teaspoons of baking soda, 1 teaspoon of salt, and 3 tablespoons of cornstarch. Gradually add this to the wet ingredients, mixing until just combined.
Pour in 1 cup of whole milk and mix until the dough is smooth.
Preheat your oven to 350°F (175°C). Take a portion of dough, flatten it, place a spoonful of the raisin filling in the center, fold the dough over, and roll it into a ball on the prepared baking sheet.
Bake the cookies in the preheated oven for 12-15 minutes or until the edges are golden brown.
