Preheat oven to 350 degrees.
Place apples in a medium mixing bowl. Pour hot water over them and allow them to sit for 10 minutes until they are rehydrated. Drain apples and coarsely chop. Combine apples with raisins, cinnamon and sugar. Stir to combine. Set aside.
Pulse oats in a food processor until they are fine. Combine oats, flour, brown sugar, salt and butter in a large mixing bowl. Stir with an electric mixer until ingredients are evenly incorporated. With the mixer running, slowly add the water just until the dough comes together and leaves the side of the bowl. Divide the dough in half.
Layer the bottom of a 9 x 13 x 2-inch baking dish with foil or parchment paper. Spray the foil or parchment paper with cooking spray.
Press half of the dough mixture into the bottom of the pan. Spread the apple raisin mixture evenly over the top. Gently press the remaining dough over the apple raising mixture.
Bake for 45 minutes until the bars are golden brown. Allow the bars to cool completely before cutting. If the bars are still a little crumbly, chilling them in the refrigerator will help them firm up.