Mushroom and walnut ‘caviar’ on herbed crostini

An easy, elegant vegetarian appetizer!

So many elegant hors d’oeuvres seem to involve meat or seafood that I decided it was time to come up with a vegetarian treat. I recall my mother eating mushrooms on toast which just looked like a nasty mess to me when I was a kid. Little did I know then that I would grow up to be a huge fan of fungi. I’m also a huge fan of baguette and love toasting thin slices to make crostini – the perfect vehicle for all sorts of spreads, dips and more. This dish reminded me of enjoying caviar on crostini at a fancy party; it’s important to chop the mushrooms and walnuts really finely to vaguely resemble the look of caviar. This dish can be served warm or at room temperature but should only be assembled right before serving so your crostini can stay crisp. If you are interested in learning more about mushrooms, check out this post about my visit to a local mushroom farm!


  • half a baguette, thinly sliced
  • 3 tablespoons (45 mL) herb-infused olive oil*
  • 2 tablespoons (30 mL) butter
  • 1 large shallot, finely chopped
  • 1 teaspoon (5 mL) finely minced garlic
  • 2 tablespoons (30 mL) white wine
  • 1/2 pound (225 g) cremini mushrooms, cleaned and very finely chopped
  • 2 tablespoons (30 mL) finely chopped, toasted walnuts
  • 1/4 cup (60 mL) heavy (35%) cream
  • 1 teaspoon (5 mL) freshly squeezed lemon juice
  • pinch cayenne pepper
  • kosher salt and freshly ground black pepper
  • microgreens, thyme sprigs or chopped fresh chives, for garnish
  • fleur de sel or Maldon sea salt, for garnish

*You can also use regular olive oil, or make your own herbed oil by gently heating the 3 tablespoons of olive oil in the microwave for 20 seconds, then adding 2 teaspoons chopped fresh herbs. Let sit 30 minutes then strain and use the infused oil.


  • Make the crostini by preheating oven to 350F. Lay out the baguette slices in a single layer on a parchment-lined baking sheet. Brush each one lightly with the herb-infused olive oil then bake 7 – 8 minutes in the preheated oven until they are just barely golden. Flip the bread slices over and bake approximately 8 minutes more until they are light golden brown. Let cool.
  • Make the mushroom caviar by melting the butter in a large, heavy-duty frying pan placed over medium heat. Add the chopped shallot and cook, stirring often, for 3 minutes. Add the garlic and cook, stirring, for 1 more minute.
  • Add the finely chopped mushrooms to the pan and increase heat slightly; continue to sauté, stirring often, for about 5 minutes or until mushrooms have softened and stopped releasing moisture. Add wine and cook, stirring often, for 2 more minutes.
  • Add chopped walnuts and cream to pan and cook 2 – 3 minutes more until most of the liquid has evaporated. Add lemon juice and cayenne, then season with pepper to taste. At this point, the mixture can sit for up to 3 hours.
  • When ready to assemble the hors d’oeuvres, you can use the mushroom mixture at room temperature, or quickly reheat it in the pan.
  • Top each crostino with some of the mushroom and walnut mixture. Garnish with microgreens or herbs, sprinkle with a pinch of sea salt, and place on a serving tray.

Serves 4 – 6.

Author: Paula Roy

Welcome to my kitchen! I love simple dishes prepared with passion and am always seeking to find new methods to make food as fun and flavourful as possible. If you enjoy this space be sure to check out my Rogers TV Ottawa cooking show, Paula Roy's Favourite Foods, available on local cable, streaming and a dedicated playlist on Rogers TV's YouTube channel.

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