I use The Educated Barfly's recipe! There's a massive blackberry bush in a park I live by so my partner and I go collect a basket full each summer and make a batch haha. But organic grocery store blackberries would be fine too obviously (if you're fine with spending the money for em lol).I usually scale this recipe down 50% and make a half batch, but Leandro's recipe is as follows:-5 cups blackberries-one 750ml bottle medium-body red wine-1.5 cups white sugar-0.75 cup London dry ginMash blackberries until pulverized in a large bowl. Pour a bottle of red wine overtop and cover with a lid or cloth and store in a cool dry place out of direct sunlight for 48 hrs.Once 2 days is up, fine strain into medium sized pot (discard the solids) and add in your sugar, heating on low until the sugar is just dissolved. Kill the heat, set aside to cool. Once cooled add your gin and bottle! I usually send the finished product through a coffee filter before bottling to make sure it's fully strained but you do you haha. Done.