Cut 4 pieces of parchment paper to a size that will fit on a standard baking sheet (also called a half-sheet pan). Place 1 piece of the cut parchment on a flat surface. Set the other pieces of parchment aside.
Remove 1 cookie dough disk from the refrigerator and unwrap it.
Use your hands to lightly dust the parchment paper with whole wheat flour. Place the unwrapped cookie dough disk on the dusted parchment paper.
Using floured hands, begin patting down the dough, flattening it to the point where you can switch to using a rolling pin. Dust the top of the dough very lightly with flour, smooth the flour across the dough with your hands, and then place a second piece of parchment paper on top of the dough. Use a rolling pin to roll out the dough until it is quite thin and within about 1 inch (2.5 cm) of the edge of the parchment paper.
Transfer the cookie dough and parchment paper pieces to the baking sheet. Transfer the baking sheet with the dough to the refrigerator to chill for 30 minutes.
Continue the same process with the remaining dough disk.
After chilling the dough for 30 minutes, place the oven rack in the middle position and preheat the oven to 350°F (177°C).
Remove the first baking sheet from the refrigerator and peel off the top layer of parchment paper.
Using a sharp knife or pizza cutter, score the dough to create 12 even rectangle shapes.
Use a fork to poke small holes in the rectangles to create an even pattern. (The holes will help the crackers remain flat and bake to a crisp texture.)
Make the topping by mixing together the cinnamon and white cane sugar in a small bowl.
Use a pastry brush or the back of a spoon to brush the rectangles with the milk, and then sprinkle a small amount of the cinnamon-sugar mixture onto each rectangle.
Place the baking sheet into the oven. Bake the crackers for 10-12 minutes or until the edges begin to appear golden brown and the crackers feel somewhat firm to the touch. (This can take up to 15 minutes.)
When the graham crackers are finished baking, remove the baking sheet from the oven and place it on a heatproof surface. Using a sharp knife or pizza cutter, cut along the original score lines with a knife. (This will make it easier to break apart the crackers once they cool.) Allow the graham crackers to completely cool to room temperature on the baking sheets.
Remove the second baking sheet from the refrigerator and repeat the baking process. Once cool, break apart the homemade graham crackers. Store them in an airtight container in a cool, dark pantry or cabinet to keep them crispy. They will stay fresh for approximately 1 week.