Combine brown sugar and butter in a saucepan. With a candy thermometer clipped on the pan, heat mixture over medium-high heat, stirring constantly. Use caution and keep stirring, and be careful mixture doesn’t begin to smoke or burn. It should take about five minutes to heat. Watch temperature climb to 290ºF. Remove from heat and pour candy mixture over the almonds in the baking dish, using a silicone spatula to scrape all the candy from the pan. While candy sets, melt your chocolate.