**A Savoury pie for Pi Day**

Pi Day is coming up in on March 14th (Get it? 3/14 for those of you who live in countries where they put the month before the date). A physicist called Larry Shaw came up with this idea in the late 80’s as a kind of geeky way to celebrate this mathematical constant. Coincidentally, this date was apparently Albert Einstein’s birthday as well. This is a festivity I can get completely behind: it reminds us of an important math concept, and we can make and eat lots of pie. What’s there not to like? Last year for the super DIY site Instructables I came up with this savoury pie for a Pi Day contest they were running. I tried to use flavours from Greek cuisine. The end result tasted wonderful, so whether it is very Greek or not is beside the point.

**What is so great about Pi anyway?**

Pi is a pretty cool math constant. No matter how big or small a circle is, the ratio between the circumference of the circle and the diameter of that same circle is always 3.14 followed by an infinite amount of digits. A woman called Emma Haruka Iwao has recently calculated Pi to 31 trillion digits. Luckily we don’t have to put all of those digits into our calculators to work out the area of a circle, otherwise it would take us our whole life-time to do one math problem (can you imagine a teacher setting THAT test?). The constant has been used for about 4000 years; first by the Babylonians and then the Egyptians. It wasn’t until Archimedes of Syracuse came along in the heady days of the 200’s BC that pi was calculated a little more precisely. The symbol for pi, which I can’t write here due to the limitations of the WordPress keyboard, was taken up by mathematicians in the 1700’s, and has become today the symbol much loved by math teachers and hated by the majority of schoolchildren all over the world.

**Pi is all around us**

So, the other freaky but tremendously cool thing about pi is that it’s everywhere in nature. Apparently, it’s a constant that comes up , well, constantly, in pretty much every aspect of the natural world from the way stripes on a zebra are set out, to the timing of division of cells in growth, to breathing cycles, to the way a pine-cone or a seashell grows. We cannot escape it, even if we want to. That’s the attraction of it for scientists and mathematicians. If they can uncover patterns of sequences of digits in pi, or why the digits are as they are, maybe they can unlock the secrets of the universe.

##### The pie made for pi

The best thing about Pi Day is that you can eat lots of pie! I used ingredients for this pie inspired from Greek cuisine. You may notice that the ingredients are in 3, 1, and 4 quantities. that wasn’t so easy to pull off, but somehow I managed! I used filo pastry to match the pie theme, but you could happily use puff pastry instead and get a great result. Actually, it may be even better to use a sturdier pastry base than filo so that the filling sits in the pie better. Let me know if you try it!

**Travel photo of the week**

I have been to Greece a couple of times, but unfortunately I don’t have any digital photos as it was way too many years ago. The next best thing I can show you is the town of Syracuse (Siracusa) in Sicily where Archimedes hung out and did all his world-shaking and moving. The old town is on an island called Ortigia, which connected to the mainland by two bridges. There are Greek ruins scattered all over the place, so it’s fairly easy to imagine the daily life that Archimedes and the inhabitants of Syracuse must have had way back then. Some of the same streets and squares that you wander on in Syracuse will be the same places where Archimedes put his feet centuries ago (maybe with a little refurbishment to the stone work since that time). Now, that’s something pretty cool to think about!

By Lisa Watson

## Greek Inspired Savoury Tart for Pi Day

### Ingredients

- 3 zucchini (courgettes) small
- 1 clove garlic
- 4 tomatoes medium-sized
- 3 eggs
- 100 g baby spinach
- 4 sprigs mint
- 3 eggs
- 1 lemon for zest
- 4 turns of a pepper mill
- 300 g Greek yogurt
- 1 tsp salt
- 4 Tbsp olive oil
- 3 Tbsp milk
- 1 packet feta cheese
- 4 sheets filo pastry

### Instructions

- Mince the garlic. Chop the zucchini in cubes. Chop the tomato in cubes.
- Zest the lemon. Roughly chop the mint leaves. Crumble the feta cheese.
- Put the oil in a large frying pan. Add the zucchini cubes, garlic, and the salt. Sauté for 4 minutes, stirring often.
- Add the spinach and lemon zest. Sauté for 3 minutes.
- Add the tomato chunks and chopped mint. Cook for 1 further minute, stirring carefully.
- Leave to cool for at least 10 minutes.
- Oil a quiche dish and place a round of baking paper on the bottom of it.
- Layer the sheets of filo pastry one on top of the other in the quiche dish.
- In a medium-size bowl, whisk the eggs and yogurt together. Sprinkle with 1/2 tsp salt.
- Add the cooked vegetables to the pie and spread them out over the filo pastry.
- Sprinkle the crumbled feta over the top.
- Pour the egg mixture over the other ingredients.
- Bake at 180 degrees C (350 degrees F) for 40 – 45 minutes, until the custard is set.