For the poolish mix all ingredients together and set apart for 1.5 hours so it can double. Best in a warm place.
When the poolish is ready put all ingredients for the dough in a larger bowl. Stir all together.
Add the poolish and mix well.
Poor the ready dough into the colomba form and spread evenly.
Set apart again in a warm place and let it double for two hours.
Just before the time is over put on the oven and preheat to 180°C/350°F
When the colomba has grown well prepare the frosting. Put just the first 3 ingredients together and stir well. Spread the mixture on the dough with care. For garnish put the almonds on the dough.
Put in the oven for 30 minutes. Tooth pick prove!
Switch off the oven and let set for other 5 minutes. Then take out and let it cool out.
The Colomba I did was (nearly) perfect. I think I let it a few minutes too long in the oven (still have to understand well how it works as it is a new one). Mine came out lightly too dry along the outer side. In the middle it was moisture and really perfect.
Who likes to put other than lemon and/or orange zest can change with chocolate chips (at least 90 % chocolate) or who likes candied fruits?