Finely chop onion, celery and carrot. Heat oil and butter in a large pan over low heat and sauté chopped vegetables, stirring.
Add chicken livers, green bile sac removed, turn up the heat and brown for a few minutes.
Deglaze the pan with white wine and allow it to reduce.
Chop fresh tomatoes and stir in. Rinse anchovies and remove bones, then add to the pan. Sprinkle with thyme leaves. Season with salt and pepper and cook for a few more minutes, covering with a lid, if necessary.
Brush bread slices with oil and toast in the oven for a few minutes, until golden crunchy.
Using a fork or food processor, mash chicken livers into a paste and spread on bread slices. Step 7 Arrange crostoni on a serving platter and serve warm.