Add the yogurt, jam, diced strawberries and milk (and vanilla if using the carafe of a blender. Process until smooth. Pour the mixture into popsicle molds filling about 2/3 full.
Using a dull knife or skewer, slide sliced strawberries down the inside of the molds so they’re visible on the outside. Add more yogurt mixture to the top to fill then freeze for 45 to 60 minutes. Remove from the freezer and add popsicle sticks. Return to the freezer until frozen solid.
To serve, run warm water over the outside of the molds until the popsicles release, making sure not to melt the popsicles. Store the popsicles in layers separated by wax or parchment paper in an airtight container.
