Preheat oven to 350°F. Lightly grease a 8×8 baking dish and set aside.
In the bowl of a stand mixer, beat together the sugar and peanut butter until light and fluffy. Beat in the vanilla, and mix until smooth.
On medium speed, mix in the flour, oats, salt, and baking soda.
Slowly add in the milk until fully combined.
Fold in the raisins, and mix until fully incorporated.
Press the dough into the prepared baking dish, and bake in the preheated oven for around 17-20 minutes, or until the bars are golden and set. Allow to cool, and cut into squares.