To Make the Sorbet
Combine the sugar, water, cherries and lemon juice in a medium saucepan. Heat until mixture comes to a boil; reduce the heat to medium low and simmer for 15 minutes until cherries have softened.
Place contents in a blender or food processor and process until smooth. Strain over a clean container to remove solids.
Add 2 tsp of cherry brandy and stir.
Freeze according to manufacturers' directions. When freezing is complete, pack into a freezer safe container and freeze for a minimum of 4 hours until firm enough to scoop.
To Make the Cherry Conserve
Put the cherries, sugar and water into a medium size saucepan. Heat until it comes to a boil and them simmer for approximately 10 minutes. Remove cherries with a slotted spoon and continue to simmer liquid until it thickens and coats the back of a spoon. Remove from heat
Coarsely chop the cherries and return to the liquid; pour all into a container and refrigerate until cold.
To Serve
Place two small scoops of sorbet into martini glasses. Fill glass with cava. Garnish with the brandied cherry conserve.