- In a bowl, beat the eggs with a whisk. Season with salt and pepper.
- In a large non-stick skillet over medium-low heat, melt half of the butter. Pour in half of the beaten eggs and top with half of the chives. Cover and cook for 2 minutes or until the omelette has set. Set aside on a plate. Repeat with the remaining butter, eggs and chives. Let cool. Cut each omelette into 3 strips of equal width. Refrigerate for 30 minutes.
- Meanwhile, on a work surface, using a bread knife, remove the crust from the bread (see note). Cover the bread with a clean dishcloth until the omelettes are ready.
- Spread out half of the bread slices. Cover each slice with 1 tbsp (15 ml) of the pesto and 1 slice of prosciutto. Divide the strips of omelette among the bread slices, folding and cutting them to fit, as needed. Top with the basil. Cover one side of the remaining bread slices with mayonnaise and place, mayonnaise-side down, over the sandwiches. Cut the sandwiches in half or into four.
If the pesto is too oily, you can let it drain in a small sieve. In this case, you will need to have a little more pesto on hand to fill the sandwiches.
You can dry out the crusts and use them to make breadcrumbs.