Preheat the oven to 350 °F and line a baking sheet with parchment paper.
Place the almonds on the baking sheet in a single layer.
Toast in the oven for about 5 to 8 minutes, using a spatula to turn them halfway. They should be golden brown.
Allow them to cool for 5 minutes, and chop roughly with a quick pulse in a food processor. Alternatively, you can buy chopped almond, and shorten the time in the oven to 2 to 5 minutes, according to how bug the chunks are. Check to make sure they’re not overdone, and turn off the oven for now.
Measure the flour, salt and baking powder into a bowl, and mix together to blend.
In a second large bowl, add the sugar and lemon zest. Use the back of a spoon to blend the two ingredients together.
Add the butter, and beat until the mixture is light and fluffy.
Beat in the eggs, then the almond extract and lemon juice, until the mixture is well combined.
Spoon in half the dry ingredients, and fold over to mix.
Add the second half of the dry ingredients, and fold into the batter.
Add the nuts when the mixture is almost blended.
When the mixture is uniform and well combined, cover the bowl with plastic wrap, and refrigerate for about 30 minutes.
When it’s ready, use a clean sheet of parchment paper to line the baking sheet, and preheat the oven to 300 °F.
Divide the dough into two equal sections, and roll each into a kind of log shape. Flatten it slightly until you get the oval shape you want.
Bake in the oven for about 30 to 35 minutes. The outside should be lightly browned.
Take the baking sheet out of the oven, and let the biscotti logs cool for about 10 minutes before cutting into slices about 1/2-inch thick.
Lay the slices flat side down on the baking sheet, and bake for another 10 minutes.
Flip them over, and bake for an additional 8 to 10 minutes. They should be quite dry in texture.
Let the cool thoroughly for at least 30 minutes before dipping into a cup of coffee or tea.
They will store, covered, in the fridge for one or two weeks.