For the Blackberry Puree:
- 2 cups or 8 oz or 250 grams blackberries
- 1/2 cup 100 grams granulated sugar
- 1 Tbsp fresh lemon juice
- 1 egg white room temperature
For the Agar Agar Syrup:
- 1/3 cup 75 ml water
- 1 cup 200 grams sugar
- 2 tsp 5 grams agar agar*
- Powdered Sugar to dust
In a medium saucepan, bring blackberries, 1/2 cup sugar and 1 Tbsp lemon juice to a simmer. Mash berries and simmer uncovered 10 min then strain through a fine sieve, pressing on the solids with a spatula. Scrape off the back of the sieve to ensure you have 1/2 cup or 125 grams of puree. Chill the puree over an ice bath until cooled.
Once puree is fully chilled and slightly thickened, combine it with 1 egg white in the bowl of a stand mixer fitted with whisk attachment.** Beat on 8-10 min on high speed or until mixture is thick and stiff peaks form. While the blackberry/egg white mixture is going, proceed with step 3.
In a medium sauce pan, stir together 1/3 cup water, 2 tsp agar agar and 1 cup sugar. Place over medium heat, bring to a boil then reduce heat to a low boil and cook 5 minutes, whisking constantly until syrup has thickened and pours from a spoon without dribbling. Remove from heat.
With the mixer on the LOWEST speed, and as soon as agar syrup is off the stove, immediately pour it in a thin stream into whipped blackberry mixture. Avoid getting syrup on whisk and bowl. Once syrup is in, scrape down the bowl and beat another 2-3 min on high speed until stiff peaks form.
Right away, transfer mixture to a piping bag fitted with a Wilton 1M large open star tip and pipe roses onto parchment-lined baking sheet, keeping the roses even in width/size.
Let homemade marshmallows stand in a draft free, low humidity, room temperature area (70˚F), uncovered for 6-12 hours, or overnight. Marshmallows will form a glossy film on top and will come off the parchment fairly easily. Once set, match 2 halves together then roll sandwiched marshmallows powdered sugar.
**If using an electric hand mixer, beat the egg white and fruit puree mixture first until stiff peaks form then start on the agar syrup since you need your hands free to whisk the agar agar syrup constantly.