Baked Parmesan and Onion Crostini

Ingredients

• 240 ml (1 cup)mayonnaise
• 100 g (1 cup)freshly grated Parmesan cheese
• 53 g (⅓ cup)minced shallot or sweet onion
• 1 loafFrench bread, regular or gluten-free
• 30 ml (2 tablespoons)minced fresh chives, for garnish
• to tastesalt
• to tasteblack pepper

Instructions

1. 1

   Heat the oven

   Preheat the oven to 200°C (400°F).

2. 2

   Mix the topping

   Stir together the mayonnaise, Parmesan and minced shallot or sweet onion. Season to taste with salt and pepper.

3. 3

   Top the bread

   Cut the bread into thin slices. Spoon some of the Parmesan mixture onto each slice and spread it evenly, then arrange the slices on a baking sheet.

4. 4

   Bake and garnish

   Bake for 8–12 minutes, until the tops are golden and bubbling. Leave to cool for 5–10 minutes, then scatter over the chives and serve warm or at room temperature.

What are Parmesan and onion crostini?

Crostini are small pieces of bread topped and served as an appetiser; the name comes from the Italian word for toasted. This American-style version uses French bread and a creamy topping of Parmesan, mayonnaise and onion.

The topping is spread over the bread before baking, so the edges turn crisp while the cheese mixture becomes golden and bubbly. Chives add a fresh finish just before serving.

Nutrition and macros by portion

The nutrition label shows one serving as written: 190 calories, 5g protein, 14g carbs, 13g fat.

The bread supplies most of the carbohydrates, while the mayonnaise contributes much of the fat and the Parmesan provides some protein and fat. Serve a few crostini alongside salad or fresh vegetables to add a lighter, fresh contrast to the rich topping.

Choosing the ingredients

Parmesan: Freshly grated cheese mixes smoothly into the mayonnaise and gives the topping a savoury, salty flavour. A finely grated texture also makes it easier to spread.

Onion: Minced shallot gives a mild onion flavour, while sweet onion is a suitable alternative. Chop it finely so the topping is easy to spread across the bread.

Bread: French bread provides a sturdy base for the topping. The recipe also works with a gluten-free loaf.

Getting the topping right

Mix the mayonnaise, cheese and onion until evenly combined, then season to taste. Spread the mixture in a fairly even layer so each slice browns at a similar rate.

A spoonful on each slice is a useful starting point; adjust the amount to suit the size of your bread slices. Keep the topping on the bread rather than letting it spill over the edges.

Watching for doneness

Bake at 200°C (400°F) for 8–12 minutes. The topping should look golden and bubbly when ready, so begin checking towards the shorter end of the time range.

Let the crostini rest for 5–10 minutes after baking. This gives the hot topping time to settle before you add the chives and serve.

Serving and timing

The full preparation and baking time is about 15 minutes, though the bread needs a brief cooling period before serving. The crostini can be served warm or at room temperature.

Arrange them on a platter as a starter or snack. Their rich, cheesy topping pairs well with a crisp salad or fresh vegetables.

Making the slices evenly

Thin, similar-sized slices help the bread crisp at a consistent pace. If the loaf is difficult to cut, use a serrated bread knife and steady the loaf on a chopping board.

Leave a little space between slices on the baking sheet so the hot air can circulate around them. If they do not fit comfortably in one layer, bake them in batches.

Recipe notes & tips

• Grate the Parmesan finely so it combines evenly with the mayonnaise.
• Mince the shallot or sweet onion finely for a smooth, easy-to-spread topping.
• Spread the mixture evenly to help the slices brown at the same pace.
• Start checking the crostini after 8 minutes, as bread thickness can affect the bake.
• Wait 5–10 minutes before garnishing so the topping can settle.
• Add the chives just before serving to keep their flavour fresh.

Variations

• Use sweet onion: Swap it for the shallot for a gentler onion flavour.
• Choose gluten-free bread: Use a gluten-free loaf as the base.
• Add extra chives: Increase the garnish for a stronger fresh, savoury note.
• Pepper it more: Add extra black pepper to the topping before spreading.
• Cut smaller slices: Make bite-sized pieces for a party platter.

Common mistakes to avoid

• Uneven slices: Cut the bread to a similar thickness so the pieces bake at roughly the same rate.
• Large onion pieces: Mince the shallot or sweet onion finely so it spreads evenly.
• Too much topping: Use a modest scoop and spread it to the edges without letting it spill over.
• Overbaking: Check from 8 minutes and take the slices out when the topping is golden and bubbling.
• Skipping the rest: Cool the crostini for 5–10 minutes before garnishing and serving.

How to store

Store cooled crostini in an airtight container in the fridge and use within 2 days. Reheat on a baking sheet in a 180°C oven until warmed through; the bread may be less crisp after storage.

Frequently asked questions