Place the blueberries in the bottom of a 3.5 quart casserole shaped crock-pot (OR a 6 quart or larger oval or round crock-pot). Sprinkle the lemon juice over the blueberries.
In a medium mixing bowl mix together the sugar and lemon zest working the zest into the sugar with your fingers to release the lemon oils in the zest. Add the flour and stir with a fork to evenly combine the flour with the sugar.
Sprinkle the mixture evenly over the berries and toss to combine well.
In a medium mixing bowl mix together the flour, sugar, lemon zest, baking powder, salt and nutmeg with a fork until everything is well combined.
Using two butter knifes or a pastry cutter cut in the cold bits of butter into the flour mixture until until it resembles a coarse meal with small pea-sized pieces of butter.
In a small bowl whisk together the eggs and vanilla extract with a fork and gently toss the egg mixture into the flour/butter mixture until moistened and the dough starts to hold together and creates clumps of dough.
Sprinkle cobbler topping evenly over the blueberries in the slow cooker,
Cover the top of the crock-pot with paper towels or a clean thin kitchen towel and place the lid on top. The toweling will absorb any condensation that will collect on the lid while cooking preventing it from dripping onto your cobbler.
Cook on HIGH for 3 to 4 hours until you can see the juice from the blueberries bubbling around the edges of the crock-pot. Always check the cobbler at the 3 hour mark and only cook for additional time if needed.
Turn off the slow cooker and carefully remove lid and toweling from slow cooker and let the cobbler cool slightly before digging in and eating it.
Scoop the cobbler warm or cooled into bowls and top with vanilla ice cream or whipped cream if desired and enjoy!