Core, peel, and slice the apples in 1/2-inch pieces. Place the apples into the skillet.
Sprinkle the granulated sugar on top and the apple pie spice. Pour the apple juice on the apples and mix well.
Cube the unsalted butter and place on top of the apples.
Cook on medium-high heat with lid on for 10 minutes. The apples will begin to soften. Reduce the heat to low and simmer for an additional 5-10 minutes.
Once the apples are soft (but not mushy), mix together the slurry of cornstarch and water.
Slowly pour the cornstarch mixture into the apples, mixing continuously so the cornstarch does not clump.
Cook for an additional minute until thick glaze has formed.