In Nesivos Shalom (pp. 73-74, based on the Toldos Yaacov Yosef) Slonimer Rebbe offers an interesting explanation of choshet, the plague of darkness: what the Mitzrim and B’nei Yisroel was both experiencing was an overwhelming spiritual light. The Mitzrim experienced this as impenetrable darkness–they were blinded by the light. Similarly, the Jews that were not prepared to leave Mitzraim could not handle the light and it killed them. The Jews who were ready to leave Mitzraim experienced it positively and for them there was light.
The analogy is made to the experience of the righteous and the wicked in the afterlife. Heaven and hell can be the same place, but the righteous can appreciate its purely spiritual nature, while the wicked find it excruciating. Why is this so? The Rambam explains that just as a sick person can taste sweet as bitter, those who are spiritually deprived perceive good as bad.
Finally tasting water after being without it for three days, B’nei Yisroel found it bitter. The Toldos Yaacov Yosef says that Torah is the water; having gone three days without studying Torah, B’nei Yisroel had a hard time appreciating its sweetness.
Three in-depth discussions of this:
Rabbi Yitzchok Alderstein, “The Painful Darkness of Light,” Nesivos Shalom, Parshas Bo, Torah.org
Rabbi Alderstein adds to this discussion an insight from Rav Moshe Midner: “‘To all Bnei Yisroel there was light in their dwellings.’ Sometimes, the light is too much for any individual to bear. When Jews dwell together, when they band together as a group to bring down Hashem’s light, they are able to jointly receive it. This is why Jews gather and sit with each other in large groups on Shabbos.”
Night and Day Lava Cakes
This can be eaten cold, although it is most fun when warm, when the molten center is all runny.
Instead of making black and white cakes, you could just prepare the chocolate batter and make all chocolate lava cakes (yield of a single batch is six cakes).
You could also make runny chip cakes by using just the light batter and filling the center with a blob of ganache (a batch of batter is enough for eight cakes; plus you will need 8 ounces of ganache, or 4 ounces coconut milk and 4 ounces bittersweet chocolate melted together). You can also use a chocolate sauce instead of ganache in the center.
If you are up to making two kinds of batter, the half and half version is better than the blondie batter with the ganache filling because it has a better ratio of chocolate to blondie dough. You could also, I suppose, up the chocolate content of the blondie batter by mixing in chocolate chips.
Blondie Lava Cake Batter (enough for 8 all blondie cakes, or 12 black and white cakes)
8 ounces flour (about 1 3/4 cups)
1 tsp. baking powder
1/2 tsp. baking soda
5 ounces oil (2/3 cup)
3 ounces brown sugar (1/2 cup)
3.75 ounces sugar (1/2 cup)
2 tsp. vanilla
To make the blondie batter, combine the sugar, oil, eggs and vanilla in a bowl. Whisk well. Rest 3 minute and then whisk again well. Mix in the flour, baking soda, baking powder and salt.
For the half blondie and half chocolate cakes, fill 12 greased and floured 4-ounce ramekins with 2 ounces of batter. To get the slanted effect, rest the ramekins at an angle so that the batter fills it on a diagonal.
Prepare the chocolate batter.
NOTE: If you are making all blondie cakes, spoon 2 ounces batter in 8 greased and floured 4-ounce ramekins and chill. Make a ganache or a chocolate sauce and chill (melt together 4 ounces coconut milk and 4 ounces bittersweet chocolate for the ganache). Chill the remaining blondie batter.
Take each chilled ramekin of batter and make a small indentation in the batter to hold the chilled ganache. Spoon 2 Tbl. of ganache into the indentation in each ramekin. Divide the remaining chilled batter into eight pieces and press out a flat piece of dough to cover the top of the ganache and seal it in. Chill the ramekins while preheating the oven to 400 degrees. Bake for 15-20 minutes, until browned and puffy on top.
Chocolate Lava Cake Batter (enough for 6 all-chocolate cakes, or 12 black and white cakes)
5 ounces sugar (2/3 cup)
1/3 cup flour
2 Tbl. cocoa powder
6-7 ounces chocolate, bittersweet, preferably 60%
4 ounces oil
Melt the chocolate and oil. Let it cool a bit.
Whip the eggs and sugar for five minutes in a large bowl (using a mixer), or until the mixture is very light and fluffy and thick. Mix in the cocoa powder and flour. Fold in the melted chocolate.
Spoon the batter over the blondie batter in the ramekins. Chill the ramekins while preheating the oven to 400 degrees. Bake for 15 minutes, or until the batter is puffed around the edges and still sunken and moist in the center.
NOTE: If making all chocolate cakes, fill 6 greased cups with batter (use 4 ounce ramekins). Can bake right away or refrigerate for baking later. To bake the all chocolate cake, bake at 400 degrees for 12-14 minutes, or until puffy and set around the edges, but sunken and still liquid in the center.