I'm not an expert on making roses, be it from buttercream, ganache or other type of icings. There are many videos on Youtube which shows you how to pipe a rose using a rose petal tip and buttercream icing or fresh cream.
This one uses buttercream icing for making roses:
This one uses fresh cream or non-dairy cream:
Don't they make it look so simple?
One thing I noticed is that in order to make bigger, opened-petal roses, use a wider petal tip and higher base. Mine didn't turn out so pretty as theirs (keras tangan sangatlah tu) but I dare say with loads of practice, yours truly could like a pro. Haha.. Yeah. Notice: with LOADS of practice.
Piping Whipped Chocolate Ganache Roses- A [Basic] Step-by-Step
You will need:
Some whipped chocolate ganache, freshly whipped or thawed at room temperature till pipeable
A piping bag
A big rose petal tip (can't help with the numbers, I used non-branded ones)
Some wafer cones (if you don't want to make your own base)
An icing rose nail/cone holder
Ganache roses- left, 1 part cream and 1 part chocolate. Right, 1 part cream and 2 parts chocolate
1. First, make the base of the rose. I couldn't be bothered so I used a wafer cone like below. Position the tip on the wafer cone, with the wide end touching the cone. While rotating your cone holder, squeeze piping bag with steady and gentle pressure, until the whipped ganache covers the top of the cone.
2. Position the tip so that the top of the tip extends higher than the base. Gently squeeze ganache in a slight arc, while rotating the cone holder at the same time. If done right, the middle of the petal should be higher than its ends. Repeat till you get 3 petals, with the ends slightly overlapping the other.
3. Make a 2nd layer of petals, 5 petals total. Place tip on the outside of one of the 3 petals with the top of the tip slightly higher than the base. Repeat squeezing and rotating motion for a second layer of petals, making sure the ends of each petal slightly overlaps the other.
3. Repeat procedure for 3rd layer of petals, 7 petals total. Sometimes I get extra space at the bottom of the rose, probably because I used a smaller rose petal tip. So I just fill in more petals until the wafer cone can't be seen (usually people stop at 7 petals).
4. Whipped ganache rose can then be transfered directly on to cake by means of a pair of scissors (sometimes I just use the end of a spatula). When I don't want to be in a rush, I just transfer the roses on a flat surface (a small plate maybe) and just store it in the freezer until it hardens and use it the day after.
****You can make ganache roses using a ratio of 2 part chocolate and 1 part cream, but it's tricky and I haven't got the hang of it yet. I think for better piping for this ratio, maybe it's better if you just leave it at room temperature overnight and use it the day after. No need to store in the fridge. Or just use it directly after being left to set for about 1-3 hours or so at room temperature. The first picture above I stored it in the freezer and thawed it the next day. It didn't pipe really well (and I suspect because I didn't use a wider tip. The long end of the tip was narrow and caused the ganache to set up hard). I think whipped chocolate ganache pipes rather like a buttercream; it's not too hard nor too soft when whipped correctly at the right temperature. As for the poor-looking rose, my bad. I very rarely pipe roses, just simple rosettes and swirls on my cakes.