Start by grinding the shelled peanuts into a coarse flour using a food processor. You want to achieve a consistency similar to almond meal. Set aside.
In a large mixing bowl, combine the softened butter and light brown sugar. Using an electric mixer, beat the mixture until it is light and fluffy, about 2-3 minutes. Add the egg and vanilla extract, mixing until well combined.
In another bowl, whisk together the all-purpose flour, ground peanuts, baking powder, salt, and cinnamon. Gradually add the dry mixture to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix!
Cover the cookie dough with plastic wrap and refrigerate for at least 1 hour. Chilling the dough helps the cookies hold their shape and makes them easier to roll out.
Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper. Once the dough is chilled, roll it out on a floured surface to about 1/4-inch thickness. Use cookie cutters to cut out shapes, making sure to create pairs of cookies for the sandwiching.
Place the cut cookies onto the prepared baking sheets and bake for 10-12 minutes, or until the edges are lightly golden. Allow them to cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.
In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from heat and add the finely chopped semisweet chocolate. Let it sit for a minute, then whisk until smooth. Stir in the strawberry jam until well combined.
Once the cookies are completely cooled, spread a generous layer of the strawberry chocolate ganache on the flat side of one cookie and top it with another cookie to create a sandwich. Repeat until all cookies are assembled.
Let the assembled cookies set for a few minutes to allow the ganache to firm up slightly before serving. Enjoy your Ampersandwich Cookies with a cup of tea or coffee, or simply on their own!