Preheat oven to 350˚F.
For candied thyme: Fully dip each sprig of thyme into the frothed egg whites, shaking off as much excess as possible. Carefully dredge each sprig in the sugar until fully coated, shaking off any excess. Place each coated thyme sprig onto a baking sheet, lined with a cooling rack and allow sprigs to dry for at least 1 hour (can be made 1 to 2 days ahead of time).
For cake: Pour flour, baking powder, baking soda, and salt into a mixing bowl and whisk together.
Pour sugar, butter and eggs into another mixing bowl and whisk together. Pour the flour mixture into the egg mixture and whisk together until very thick and combined.
Stir in the remaining ingredients until fully incorporated and the batter is smooth.
Pour the batter into three prepared cake pans (bottoms lined with parchment and lightly greased) and bake for 25 to 30 minutes or until a toothpick comes out clean when inserted into the center of the cake.
Allow the cakes to cool in the pans for 15 to 20 minutes before removing from pans and allowing to cool completely.
For frosting: Place butter, cream cheese and honey into a stand mixer, with a paddle attachment (or using n electric hand mixer), and whip until light and fluffy. Add sugar, ½ cup at a time, until fully incorporated and most of the lumps disappear. Add vanilla and continue to beat together until light and fluffy. (If frosting is too stiff add milk, 1 tablespoon at a time, as needed).
To assemble: Place a thin layer of frosting over the top of one of the cakes and top with the other cake, inverted (so both cake circle tops are touching one another). Repeat with remaining cake layer, so all three are stacked atop one another.
Gently frost the entire cake with a thin layer of frosting.
Place a ‘crown’ of thyme sprigs around the base and top of the cake and continue to decorate with other edible flowers and petals. Serve.