In the bowl of a stand mixer, fitted with the whisk attachment, whisk together the yogurt and sugar until sugar is dissolved. Stir in puree, then add lemon juice and salt to taste.
Add and churn the mixture to the ice cream maker according to manufacturer's instructions. Pour churned yogurt into a freezer-safe container, cover and freeze for 3 to 5 hours. You can skip the freezing and enjoy it as soft-serve.
Make the waffles:
Over low heat, melt the butter and chocolate together in a small saucepan. Set aside to cool.
Use a hand whisk to whisk the eggs until light and fluffy. Whisk in the milk and vanilla bean paste. Combine with the sugar.
Sift the dry ingredients together and combine with the egg mixture until smooth.
Cook according to your waffle's maker's instructions.
Make the chocolate shell:
Melt chocolate in 10-second intervals in the microwave. Stir in oil until fully combined. Allow to cool.
Assemble the sandwiches:
Use a cookie cutter to shape the frozen yogurt and sandwich between two waffles. Dip in chocolate, allow a few seconds to set, then wrap and return to the freezer until ready to enjoy.