With a mixer, beat heavy whipping cream until thick. Pour in sweetened condensed milk and lemon extract and fold in until smooth.
Next, pour half the ice cream into a freezer safe container. Top with half of the blueberries. Repeat with another layer and top with the remaining blueberries and slices of lemon.
Freeze for 5-6 hours or overnight. When it is time to serve, remove from freezer and let sit on the counter to soften for 5-10 minutes before serving.