1cup + 2 1/2 Tablespoonsall purpose flour, unbleached flour recommended, spooned and levelled to measure
1/2cupDutch-processed cocoa, *see Note 1 below
3/4teaspoonbaking soda
1/4teaspoonfine salt, omit if using salted butter
1/4ozunsweetened chocolate, *see Note 2 below
5Tablespoonsunsalted butter, cold, cut into 1/2-inch chunks
3/4cupwhite granulated sugar
1/2teaspoonvanilla, or vanilla bean paste
1 1/2largeeggs, at room temperature *see Note 3 below
Icing/confectioners' sugar, for garnish
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Instructions
Take eggs out of the fridge to come to room temperature (25-30 minutes ahead).
Preheat oven to 350F (not fan-assisted). with rack in centre of oven.
Prepare an 8.5 x 4.5-inch or 4 x 9.5-inch loaf pan by spraying with cooking spray, then covering the bottom and sides with parchment paper, letting the parchment extend beyond the sides an inch or so. (If not using parchment, butter and flour the pan really well). *If you only have a 9x5-inch pan, it will work. Your loaf will be longer, wider and shorter, so expect that it will cook through more quickly and check it earlier.
Measure out the milk. Add the lemon juice to the milk. Stir and let stand while you continue with the batter. (The lemon juice will cause the milk to curdle, so don't be alarmed later on when it's a bit chunky :)
In a medium bowl, whisk together the flour, cocoa, baking soda and salt (omit added salt if using salted butter). Set aside.
Melt the 1/4 oz of chocolate, either in the microwave for about 30-40 seconds or alternately heat about 1/2-inch of water in a saucepan, remove from heat, then place the chocolate into a ramekin and place the ramekin to sit in the water to melt it. *Make sure no water gets into the ramekin or the chocolate will seize. Stir the chocolate until smooth, then set it aside to cool to tepid while you continue with the batter.
In a large bowl with an electric mixer or the bowl of a stand mixer fitted with the paddle attachment, beat the cold butter cubes on medium-high until smooth, about 1 minute. Gradually beat in the sugar. Once all the sugar is added, add the vanilla. Beat the mixture until very light in colour and texture, scraping down the bowl occasionally, about 4 minutes. Gradually beat in the eggs. Reduce the mixer speed to low. Beat in the cooled chocolate.
Add the flour mixture alternately with the milk, beating well after each addition and scraping down the bowl between additions. (start with 1/3 of the flour, then 1/2 the milk, another 1/3 of the flour, remaining milk, then remaining flour).
Pour batter into prepared loaf pan and smooth the top.
Bake loaf in preheated oven for about 50 minutes for a 4x10-inch pan. *Baking time will vary for the 8x4 or 9x5-inch pans, so check and test often after about 45 minutes of baking. Test with a skewer in the centre. The tester should come out fairly dry and clean, with maybe a dry crumb or two on it. The sides of the cake should have pulled away from the side of the pan and the top should be puffed and cracked. The top will spring back when gently pressed with your finger.
Cool the cake in pan for 10 minutes, then lift out of the pan by grabbing the parchment paper sides. Set onto cooling rack and gently remove the parchment to allow the loaf to cool completely. Store at room temperature, wrapped, for up to 2 days. Cake will also freeze well.
Notes
1. You will need to use a Dutch-processed cocoa here and not natural cocoa. This recipe has not been tested with natural cocoa and may not work as intended if you use natural cocoa powder. 2. Yes, it really is just 1/2 oz! But unsweetened chocolate is pure chocolate, so a little goes a long way. I haven't tested this recipe with bittersweet or semi sweet chocolate. It should technically "work", though the chocolate flavour will be reduced. 3. To get 1/2 an egg, break egg into a small bowl and mix with a fork. Discard half of it, then add the other full egg to the bowl, to get 1 1/2 eggs.Be sure to read the FAQ above the recipe card for more tips for making this recipe.