Preheat oven to 400ºF. Place a parchment-lined baking sheet on the lowest rack to catch any drips.
Combine sugar and water in a small saucepan over medium heat and stir until sugar dissolves. Stir in dried rose petals and let stand while you prepare the rest.
To make topping, whisk together flour, baking powder, and salt. Using the large holes on a box grater, grate the butter directly over top. Whisk again to combine. Pour in the milk and fold it into the dry ingredients with a light hand, being careful not to overmix (the mixture will be very lumpy, but no dry flour should remain).
Toss the strawberries with the flour in a 1-1/2 litre (1 1/2 quart) baking dish (I used a deep pie dish). Pour the cooled rose syrup through a fine-mesh strainer directly onto the berries, pressing on the rose solids to extract as much liquid as possible. Toss to combine.
Spoon the biscuit topping onto the berries and bake on top of the prepared baking sheet for about 30 minutes, until filling is bubbling vigourously around the sides and the topping is golden brown.