2 ears sweet corn
1 1/2 cups half-and-half
1/3 cup sugar, plus additional for the blackberries
1/4 tsp salt
1/2 tsp vanilla
heaping 1/2 cup blackberries
Cut the kernals off of the cob, and place in a saucepan. Hack the cobs up in a few pieces, and add them as well, along with the half-and-half, 1/3 cup sugar, and salt. Bring the mixture to a simmer for a minute or so, until the corn softens and turns a darker yellow. Turn off the heat, add the vanilla, and let the mixture steep for an hour, transferring to the refrigerator as it cools (you want to wait a minimum of an hour to let the mixture infuse, but you can shelve it in the fridge for longer if needed).
While the corn mixture is steeping and cooling, rinse the blackberries and mash them with a fork or potato masher. Sweeten to taste with a spoonful or two of sugar -- the corn mixture will be sweet as well, so you want the blackberries to be a bit tart for contrast.
After the corn mixture has steeped, fish out the cobs and discard. Puree the remaining mixture in a blender, then strain through a fine sieve (you may have to clear the strainer a few times to get rid of the corn solids). Place the corn mixture in a container with a spout, and pour an inch of it in the bottom of your popsicle molds. Top with a spoonful of the sweetened blackberry puree, then repeat the process until the molds are filled (leaving enough headspace for them to expand). If you have the kind of molds with stick handles attached, simply freeze until solid. Otherwise let freeze half an hour, insert popsicle sticks into the semi-frozen mixture, and freeze completely.