In your blender or food processor, puree the bananas, lemon juice, and brown sugar until smooth. Set aside.
Meanwhile in the bowl of your stand mixer, whisk the egg yolks until they become light and frothy. In a saucepan, heat the milk with the sugar, until combined. Do not boil. To temper the eggs add a couple tablespoons of the hot milk mixture into the stand mixer while whisking on low. Then slowly add all the milk mixture and continue to mix. Now pour this mixture back into the saucepan and on the stove on low heat and stir constantly until it thickens. This may take a few minutes.
Pour the heavy cream into a large bowl, and then strain your custard (milk) mixture in. Add the banana puree and mix well. Let this cool to room temperature, and then refrigerate until cold. This may take 1-4 hours.
Next follow your ice cream maker's manufacturer’s instructions for churning (I use the Kitchenaid Ice Cream Maker attachment), usually about 20 minutes. At 12-15 minutes add the sprinkles ( best to add when it’s closer to done churning, or the sprinkles may begin to bleed into your banana colored ice cream.
Remove from the ice cream bowl and place in a freezer safe container, covered, overnight, and enjoy the next day!