Heat the blackberries with 2 teaspoons of water in a medium-sized pot over medium heat, stirring every few minutes until they soften and break apart, using the end of your stirring spoon to help crush them. Lower the heat and allow the mixture to simmer for 15 minutes. Remove 2 teaspoons of the blackberry reduction mixture and set it aside. Stir in the sugar, honey, and lemon juice and allow the blackberry jam mixture to continue simmering over low heat until thickened, about 20 minutes, stirring every 5 minutes or so. Remove from heat, stir in the lemon zest and cardamom, and allow to cool to room temperature then refrigerate.

In a small bowl or cup, whisk together the cornstarch and lemon juice until combined. Set aside.

Preheat the oven to 250 degrees Fahrenheit. In the bowl of an electric mixer fitted with the whisk attachment, beat the egg whites at low speed, gradually increasing the speed to medium. When the whites start to hold soft peaks, you can begin adding the sugar 2 tablespoons at a time, and wait until that sugar has dissolved before you add next couple tablespoons. Continue beating until glossy, satiny peaks begin to form. This whole process will take about 15 minutes. Do NOT beat the egg whites at too high of a speed.

Add the cornstarch mixture to meringue mixture and beat for another minute until cornstarch mixture is incorporated, then fold in the vanilla extract and the ground cardamom.

Trace an 8-inch circle on a piece of parchment paper, then flip it upside down and place it on a baking sheet down so the traced side won't touch the meringue. Lift up each corner of the parchment paper and dab a small teaspoon-sized blob of meringue on the corner of a large baking sheet, then press the parchment paper back down firmly onto the bit of meringue (doing this on each of the four corners of the baking sheet will keep the parchment paper from sliding around while you spread your pavlova shape).

Using a rubber spatula, spread the remaining meringue into an 8-inch circle shape using the tracing to guide you. Try to make the edges of the pavlova slightly higher than the center to allow space for the toppings later on. Use an offset spatula to make vertical lines around the edge of the pavlova, starting your offset spatula at the bottom of the pavlova and then lifting straight up, and repeating all the way around the edges of the pavlova (optional).

Place the pan in the oven, reduce the temperature to 225 degrees Fahrenheit and bake for 90 minutes, or until the meringue is crisp on the outside and easily lifts off the parchment. Turn off the oven and allow the pavlova to cool to room temperature over several hours. Pavlovas will deflate and collapse if cooled too quickly. Once cooled, remove the pavlova from the oven.

If your pavlova has cracks, do not fret. If any part looks like it may crack off after cooling, just gently press it back into place (the toppings will help hide any large cracks on the top).