In a stand mixer, whip the heavy cream until stiff peaks form, about five minutes. Fold in the mascarpone and condensed milk, and blend until smooth.
While the cream and mascarpone are mixing, puree the blueberries and lemon juice in a food processor or blender. Pour into the cream base, and add the lemon zest and vanilla. Mix well.
Line a bread pan with parchment paper and pour the ice cream base into the pan. Spread evenly, cover, and refrigerate for at least 8 hours or overnight.
When ready to serve, let the ice cream sit out for about five minutes to soften, then scoop and serve in waffle cones. Dip in the crushed gluten-free graham crackers for an extra crunch. Enjoy!