In a medium mixing bowl, whisk together the eggs, pumpkin puree, evaporated milk, brown sugar, granulated sugar, salt, and pumpkin pie spice until smooth and well combined.
Unroll the refrigerated pie crust onto a sheet of parchment paper. If using an oval slow cooker, gently roll the crust 1–2 inches longer to create an oval shape. If using a round slow cooker, no rolling is necessary.
Carefully transfer the parchment paper and pie crust into a 6-quart slow cooker. Press the crust evenly into the bottom and slightly up the sides. Trim any excess parchment paper so only a small amount extends beyond the crust.
Pour the pumpkin filling into the prepared pie crust and spread it into an even layer.
Cover and cook on HIGH for 3 hours and 15 minutes, or until the filling is set in the center.
Turn off the slow cooker, remove the insert, and let the pie cool for 30 minutes.
Using the parchment paper, carefully lift the pie out of the slow cooker and transfer it to a wire rack to cool completely.
Slice and serve with whipped cream, if desired. Refrigerate any leftovers.