50 gm (½ cup)multigrain breadcrumbs50 gmbutter, plus extra for greasing6leeks, thinly sliced2garlic cloves, finely chopped100 gmGruyère, coarsely grated125 ml (½ cup)pouring cream4eggs, whisked1/3 cupcoarsely chopped tarragon leavesSeeded mustard salad1 tbspextra-virgin olive oil2 tspwhite wine vinegar½ tspseeded mustard50 gmbaby leaf salad
Preheat oven to 200C. Lightly grease four 10cm-diameter spring-form pans and dust with breadcrumbs, shake off excess and reserve. Heat butter in a large frying pan, add leek and garlic and cook over medium heat until leek is soft (5-7 minutes). Set aside to cool slightly. Meanwhile, combine all the remaining ingredients and reserved breadcrumbs in a bowl, stir to combine and season to taste. Add leek mixture to cheese mixture, spoon into prepared pans and bake until golden and cooked through (10-12 minutes).
Meanwhile, for seeded-mustard salad, combine oil, vinegar and mustard and season to taste. Place salad leaves in a bowl, drizzle with dressing, and toss gently to combine. Serve tart warm or at room temperature with salad.