In a sauce pan, pour 8 oz. raspberries, 1 tsp. fresh rosemary (leaves of 3 or 4 sprigs) and 1½ tbsp. sugar. Turn on a medium flame. Break the raspberries apart with a spoon while they simmer with the sugar. After about 3 minutes, lower the heat and allow the berries to simmer, bubble and reduce for 10-15 minutes, stirring occasionally.
Spoon raspberry mixture into a small mesh strainer over a bowl and press the compote through the strainer to separate it from the seeds and rosemary. Your compote should be semi-gel-like. If it’s runny like juice, give it 5 more minutes to reduce in your sauce pan. If it's still not quite a gel-like texture, add 1-2 tsp. of corn starch to thicken it up a bit. Cover with cellophane and place in the fridge.
Add 1 cup of white chocolate to a double boiler, or simply place it in a glass pyrex measuring cup in your sauce pan. Add a small amount of water to the pan and turn the heat to medium. Allow the chocolate to melt while you prepare your other ingredients, mixing occasionally.
Add 1 cup heavy whipping cream to a mixing bowl and use a hand mixer (or add to a standing mixer) on a high setting to whip the cream until thick. You’ll know it’s ready when small peaks form when you lift the beaters. Once cream is whipped, add 12 oz. whipped cream cheese, 1½ tbsp. real vanilla extract, and 1 tsp. sugar. Mix ingredients thoroughly.
When the chocolate is finished melting (it takes about 10 minutes) give it a nice stir and make sure no chocolate is unmelted. Add melted chocolate to your mixing bowl and mix all ingredients together thoroughly. Once mixed, place in a container with a lid and refrigerate for at least 4 hours.
Once your mousse is set, place your pastry tip in the pastry piping bag and seal it shut with a twisty tie just above the tip. You’re going to be pressing the white chocolate mousse into the bag, and you don’t want it to come out just yet.
Fold the top of the bag over a little (this makes things less messy when you’re ready to squeeze the bag), and place in a large cup or mason jar to keep it standing up. Add a heaping tablespoon of mousse to the bag and push it all the way down to the bottom with a spoon. Place the bag back in your jar and spoon in a teaspoon of raspberry-rosemary compote, making sure it’s spread over the mousse. You can be a little sloppy here. It makes for a nicer marbling.
Repeat the process by adding another heaping tablespoon of mousse, then a teaspoon of compote in layers until you fill your bag. You can either seal the top with a twisty tie and place your bag back in the fridge for when you’re ready to serve, or remove the bottom twisty tie and fill your glasses.