Roll out some of the fondant icing and cut out four flowers of increasing sizes for the pink-tipped succulents, or 11 individual leaves and a star for the spiked succulents. Roll over the edges of each petal with a pencil to thin them out, then pinch the ends together to form a point. Using the offcuts, make a small bud with a piece of icing to sit in the centre. Remove one of the petals from the smallest flower or star and moisten the middle with water. Place the bud in the centre and gently fold and press the remaining petals around the bud, pressing so they adhere to it. Gently tease the tops of the petals so they sit away from the bud. Make a shallow bowl with some crushed tinfoil. For the pink-tipped succulents, put the largest rose in the middle. Moisten the centre with water and place the next smallest flower in the centre, so the petals don’t align. Repeat with the final rose. For the spiked succulents, dampen the thin ends of 7 of the leaves with water, then overlap them together to form a flower shape. Moisture the centre with water. Pinch the thin ends of the remaining four petals so they're slightly cupped, then press them into the centre of the large flower so they overlap, making sure the petals don’t align. With both sets of succulents, put some folded pieces of paper towel between each layersof petals so they're elevated. Moisten the centre with water and put the bud in the centre. Repeat with the kitchen towel. Rest the tinfoil in the indents of a muffin tin and leave to dry out for at least 12 hours. Dust the edges of the pink-tipped succulents with glitter spray.
Preheat the oven to 180°C/fan 160°C/gas mark 4. Sift the plain flour, cocoa powder, bicarbonate of soda and baking powder into a large bowl. In a separate bowl, whisk together the sugar and eggs. Add the vanilla bean paste, oil and milk to the eggs and whisk to combine. Add the wet ingredients to the dry ingredients with 120ml boiling water and gently fold until everything is incorporated and you have a smooth batter that's quite runny.
Line a muffin tin with 12 cases and, using a small ladle, divide the mixture between the cake cases until each is about two-thirds full. Bake in the oven for 15-20 minutes, or until a cake skewer comes out clean. Transfer to a cooling rack and leave to cool completely.
Put the chocolate in a small bowl and microwave on medium for 1-1½ minutes until melted. Leave to cool. Put the softened butter in a freestanding mixer and beat for a minute or so. Add half the icing sugar and beat until incorporated. Repeat with the rest of the icing sugar. Add the melted chocolate and beat again until the chocolate is incorporated and you have a smooth buttercream.
Slice the cupcakes so they're level on the top and add 1 tbsp icing to each, smoothing until it covers the surface. Sprinkle each with the Oreo crumbs, pressing them down to ensure they stick to the icing. Put a little drop of icing on the bottom of the succulent and then place on the cake, pressing down gently so it stays.