bowl, whisk the eggs with the remaining sugar for 30 seconds Whisk in the lemon juice mixture and add the zest Create a water bath by bringing 1 inch of water to a simmer in a medium saucepan Rest the bowl with the egg and lemon mixture on the saucepan, making sure that the bottom is not touching the simmering water (otherwise the eggs will scramble) Place a digital thermometer in the bowl and whisk the mixture over the water bath until it thickens and reaches 176° to 179.6°F/80° to 82°C The speed of the whisking is not important, but it is crucial to whisk all the time and everywhere Ignoring a side of the bowl will result in scrambled eggs Immediately remove from the heat and strain into a bowl, using a rubber spatula to push the mixture through a fine mesh strainer Allow to cool to 140°F/60°C; this should not take more than 5 minutes Then add half of the soft butter and blend with the immersion blender Add the second half of the butter and blend When all of the butter has been added blend for another 30 seconds to a minute, until smooth and homogenized You can also use a blender for this step 6 Pour the lemon cream into the baked and cooled crust Refrigerate for at least 2 hours before serving; the cream will set and you will be able to get clean slices when you cut the tart Shortly before serving decorate the top with the meringues, arranging the round meringue in the ...bottom is not touching the simmering water (otherwise the eggs will scramble) Place a digital thermometer in the bowl and whisk the mixture over the water bath until it thickens and reaches 176°... to 179.6°F/80° to 82°C The speed of the whisking is not important, but it is crucial to whisk all the time and everywhere Ignoring a side of the bowl will result in scrambled eggs Immediately remove from the heat and strain into a... spatula to push the mixture through a fine mesh strainer Allow to cool to 140°F/60°C; this should not take more than 5 minutes Then add half of the soft butter and blend with the immersion blender Add the second