In a medium saucepan, 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 Raspberry mixture. Once syrup is in, scrape down the bowl and beat another 2-3 min on high speed until stiff peaks form.
Instantly 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 room temperature area, uncovered for 6-12 hours, or overnight. Marshmallows will form a glossy film on top and will come off the parchment fairly easily.