Ingredients :

• Walnuts — Take whole kernels and crush them yourself rather than buying pre-ground nut meal. Irregular pieces provide crunch to some bites and melting softness to others — that’s what makes the texture. Use high-quality local walnuts if you can find them, but standard walnuts work just fine.
• Butter — Softened at room temperature, not melted. Butter that is too melted makes the batter greasy and compact instead of creamy. Set it on the counter 30 minutes before starting. Use semi-salted butter if you like — it subtly enhances the walnut flavor without being obvious.
• Eggs — Three whole eggs, also at room temperature. A cold egg straight from the fridge will slightly seize the creamy butter, and you’ll end up with a batter that looks curdled. It’s not catastrophic, but better avoided.
• Vanilla — Optional on paper, essential in practice. It rounds out the aromas and gives depth to the whole cake. A teaspoon of extract is enough. No vanilla? A little grated orange zest does a similar job and pairs beautifully with walnuts.