Sift the flour, icing sugar, almond flour and salt into a large mixing bowl. Chop the vegan butter into chunks and add to the bowl. Massage together with your hands to form a shaggy dough.
Pour in the agave and vanilla extract and mix to combine. Turn the dough onto a clean work surface and bring together to form a dough ball. (If the dough seems too wet, add up to 2 tablespoons more flour and knead to combine. See notes for my preferred vegan butter brand). Cover the dough with reusable wrap (or plastic wrap) and chill for at least 1 hour.
Preheat oven to 350F/180C. Line two baking sheets with parchment paper. Sprinkle the work surface with flour and roll the dough into a sheet, 1/4-inch thick. Cut round circles into the dough using a round cookie cutter, (I used a 2½-inch/6½ cm cutter).
Place the cookies onto the baking sheets and pop back in the fridge. Gather the dough scraps together to reform a dough ball, and roll out one more time, 1/4-inch thick. Cut out more cookies with cookie cutter. Place onto the baking sheets.
Bake the cookies for 12 minutes, or until the cookies are lightly golden in colour. Let cool slightly, then transfer to a wire rack to cool completely.
Make the glaze by sifting the icing sugar into a mixing bowl. Add the almond milk, a tablespoon at a time, and whisk together. (Add more almond milk, a teaspoon at a time, if desired for your preferred glaze consistency).
Turn the cookies upside-down and dip into frosting to coat the tops. Place back on the baking tray, icing side up. Garnish with dried rose petals and candied sprinkles. Enjoy as is, or place the cookies in fridge until icing has hardened (about 2 hours).